HELP PLEASE: Improving HTPC Stereo Audio Quality?

[Nikko]

Hi,

 

As a new member from Australia can I just say I'm VERY impressed by everything at this website & hope it will be able to provide some great info on getting great stereo audio quality from ones HTPC - something many other HTPC sites overlook IMHO.

 

I've been running a MCE 2005 based HTPC for a few yrs now and until recently always ran my motherboard's onboard audio via optical SPDIF through my Yamaha AVR. Though I had a $2000+ set of 5 quality speakers the results were pretty average.

 

So I've sold the AVR.....sold the set of 5 high end speakers and wanting to get the best possible audio at a REASONABLE price through my HTPC and use only 2 speakers.

 

Pls note: My entire audio collection has been ripped using EAC into FLAC. I only listen to 44.1khz material.

 

A few questions I have and would LOVE feedback on are:

 

1) High End Soundcard or Entry-Mid External DAC?

My current thinking is that better value & still very good results could be gotten by using a high quality soundcard eg Asus Xonar STX, Auzentech Forte - via the analogue audio out connections - AS OPPOSED to using the onboard audio via USB/SPDIF to an external DAC.

 

I'm sure HIGH level external DACs would be superior but my thoughts are that the Xonar STX would be SIGNIFICANTLY superior to any approx. $Aus250 external DACs - which is around the absolute entry level for external DACs in Australia.

 

Does this seem logical?

 

 

2) Power Amp vs Integrated Amp?

This query is conditional on the use of a soundcard, rather than an external DAC.

 

As I have been told that if using RCA analogue outs on a soundcard you can bypass the need for a pre/integrated amplifier and simple use a power amplifier. This is attractive to me as I have an NAD 2200 power amp that is reasonably well regarded for an older amp.

 

All volume control would be done PURELY through the HTPC's interface.

 

Is this viable? Any possible reasons why an integrated amp would be superior?

 

I have heard that a concern is that the signal from the soundcard would have to be weak (low) and so the SNR would actually be quite high because of this - which takes away from the soundcards main strengths.

 

 

3) Kmixer - the truth behind the myths?

I find it really hard to get the absolute truth on this - so would welcome some clarification as people tell me one thing then someone else the exact opposite!

 

So:

 

1) Does Kmixer cease to be a factor on Vista & Windows 7?

 

2) Does Kmixer touch/resample all audio output in an XP environment? eg many say it doesn't affect a digital stream...others say its affects ALL eg spdif/usb/analogue?

 

Thank you in advance for your assistance and any feedback you may have.

 

:-) Nikko

 

 

 

[Audio_ELF]

Hi Nikko, welcome to the forum. I'll try to answer your questions though other people will have different answers for you. Many of them right, even though some will contradict what others say. There (so far) is no absolute truth.

 

1) High-end sound-card or entry/mid level DAC

My personal preference would be for a separate DAC. My reasoning for this is that by having your DAC external and connected via USB (or SPDIF), you remove all the sensitive audio electronics from inside your computer which can cause interference. Also by having an external DAC you can move the PC further your audio stack. I will qualify this by saying I've never done any comparison between the Xonar sound-cards and DACs. If you are using the onboard sound-card and SPDIF connector this may be changing the sample rate of your audio. I would personally bypass the onboard and stick with USB as the simplest option.

 

2) Power amp vs. Integrated amps.

First off, I would say that ideally you should avoid any computer based volume controls. As you are talking about lower end DACs, etc. I'm assuming you are considering using iTunes / Foobar / Media Monkey software. None of these provide volume controls that are effective without reducing the sound quality for critical listening.

However that doesn't automatically mean you needs a pre-amp or integrated. There are several DACs available that include pre-amp / volume functionality if you are using a one-source or digital only system.

 

3) Kmixer ...

Yes there are lots of truths and myths out there. Two good articles support that Kmixer can be bit-perfect. Kent Poon wrote http://www.designwsound.com/dwsblog/?page_id=1607 supporting the idea that iTunes on XP can be bit perfect using CD quality files and dCS (a very high end DAC manufacturer) published http://www.acourate.com/OperatingSystemsHandlingOfSampleRates.pdf which also agrees and also examines Windows Media Player.

Other people will tell you different things based on their subjective listening tests.

Apart from KMixer, factors such as jitter and possibly other (unknown) factors can influence the absolute sound quality heard from different software applications.

 

Best wishes to you with your HTPC project.

Eloise

 

P.S. Sorry in answering I missed the fact you are using Windows Media Centre - you may find it easier to get best quality by swapping to using either Media Monkey, J.River Media Centre or Foobar as these allow you to bypass the Kmixer entirely.

 

[Nikko]

Hi Eloise,

 

Firstly, let me say thank you for a very well thought through answer - marvelous work!

 

I just had a few points to both reply on and also perhaps clarify:

 

My personal preference would be for a separate DAC. My reasoning for this is that by having your DAC external and connected via USB (or SPDIF), you remove all the sensitive audio electronics from inside your computer which can cause interference.

This is good point and Asus have gone to considerable lengths to ensure that EMI and RF interference isn't a factor on the Xonar STX with a significant metal shield, that acts as a faraday cage. This is the latest review of the card:

http://www.overclockersclub.com/reviews/asus_xonar_essence_stx/

 

Would you still feel that the environment would influence the cards performance? I know safer is probably better, though Asus really have targetted this card at audiophiles so I'm open minded that they could achieve this.

 

I guess my main thought process behind the STX or equivalent soundcard is that for the money spent it will provide a considerably superior end result to that I could get from an external DAC. I don't doubt the logic that I could possibly get a better result from an external DAC thats twice the cost etc......but I'm unsure if one in the same price ballpark would be competitive?

 

So I guess for that money I'm looking at DACs like the Valab NOS DAC.....Pro.DAC MkII....or similar - and comparing those to the STX etc seems very hard to do/find info on.

 

However that doesn't automatically mean you needs a pre-amp or integrated. There are several DACs available that include pre-amp / volume functionality if you are using a one-source or digital only system.

Oh thats interesting, I wasn't aware of these - though perhaps they're completely cost prohibitive - especially in our sheltered little market where everything tends to sell for double the US/European prices.

 

I would personally bypass the onboard and stick with USB as the simplest option.

Ah, okay I wasn't sure about this - of course on the assumption one's using an external DAC but this makes some sense.

 

Forgive me for jumping to a subject addressed ahead , but does using USB for singal output from your system circumvent and avoid the resampling of Kmixer? Or do you still have to use ASIO etc to get around it even via USB?

 

First off, I would say that ideally you should avoid any computer based volume controls. As you are talking about lower end DACs, etc. I'm assuming you are considering using iTunes / Foobar / Media Monkey software. None of these provide volume controls that are effective without reducing the sound quality for critical listening.

I'm unsure what you mean by lower end DACs in this context? Is this following on from the assumption that external DACs are superior? As for example the DAC in the Xonar STX, the Texas Instruments PCM1792A is meant to be very good.

 

Though this ties in what what I'd be told in that for best results your source signal should be at maximum strength with the end volume only being influenced by the amount of amplification applied.

 

Thank you also for those articles on Kmixer - I will read those with great interest as its a very confusing area with mixed messages on it all over the place.

 

Thanks again for a great reply.

 

:-) Nikko

 

[Audio_ELF]

As I say I've never listened to any of the Xonar cards so it's difficult for me to comment ... personally I'd stick with a DAC but thats probably me being prejudiced against sounds-cards from Sound Blaster Audigy (and before) days.

 

DACs with built in volume controls include the Beresford which is around £150 (sorry not sure what it would be in Aus) then, and I've probably missed several out along the way, something like the Benchmark DAC1 or Lavry DA10 that comes in at £1000 plus. The other disadvantage of (most) DACs with volume control is that they are not remote controllable.

 

Forgive me for jumping to a subject addressed ahead , but does using USB for singal output from your system circumvent and avoid the resampling of Kmixer? Or do you still have to use ASIO etc to get around it even via USB?

Just by using USB you don't circumvent Kmixer.

 

I'm unsure what you mean by lower end DACs in this context? Is this following on from the assumption that external DACs are superior? As for example the DAC in the Xonar STX, the Texas Instruments PCM1792A is meant to be very good.

I was more thinking in cost terms - wasn't disparaging the DAC chip in the Xonar card. I was more referring to the fact if you use Amarra (for instance), then the volume control is meant to be very good and you'd be worried less about using such a software volume control. In iTunes, Windows Media Player, etc. the volume control isn't so good. There are also some DACs (Weiss, Wavelength, etc) that use either high quality digital volume controls or computer controlled analogue volumes which are excluded from my generalization about volume controls.

 

Even reading the articles won't completely solve your issues on KMixer probably - though they are written by people who's products I have respect for.

 

Hope I've helped a little more ...

Eloise

 

[Nikko]

Oh you've helped a lot - so thank you.

 

Yes, I know in the past soundcards were very much limited by the EMI in the computer case and other factors but the Xonar STX is hyped to be the first real audiophile soundcard.....the reviews have all been outstanding but I'm yet to see one where its put up against a quality external DAC and not found anyone who's able to speak from expereicne about this or a similar comparison - so is very hard to figure out.

 

I do tend to think that connecting the source to a power amp PROBABLY isn't the best idea though - and an integrated amp is a better option. Volume control through the computer is kinda a little scary....especially with a power amp like the NAD 2200, that can put out as much as 2x400w if need be! We've all seen windows do weird things and a blast like that'd take a few yrs of your life!

 

I guess with an integrated you'll always have FULL volume control - and can have the source at MAX signal strength all the time - so getting the best SNR from it.

 

Hmmmm now you've got me all downhearted as I thought I'd find all the answers about Kmixer in those articles....oh well more info is good anyway.

 

Thanks again for your fabulous replies.

 

[Audio_ELF]

You wrote "Hmmmm now you've got me all downhearted as I thought I'd find all the answers about Kmixer in those articles....oh well more info is good anyway."

 

I have read them and feel that their results are good enough evidence for me that I don't need to worry. Though other people have said they hear different results. If dCS (who's integrated CD player is about £10000 and DACs go upwards from there) say that it's bit perfect to their mind then I'm happy to accept their word.

 

As for integrated ... have you thought about getting a NAD (or other) pre-amp ... might be difficult to audition though worth a thought.

 

Eloise

 

[Nikko]

Thats a VERY good point you make about Kmixer and the chap with the very expensive gear saying its all but as good. Hard to argue and I saw a thread somewhere that said basically the same. It was to the gist of that in real terms any altering of the data stream by Kmixer is sooooooo tiny that no-one would be able to tell the difference. The placebo effect is ever so powerful in audio land so I thought this made sense too.

 

Of course, then you'll get a dozen folks saying ASIO made a huge difference - so go figure. :-)

 

Haha I was literally JUST writing on another forum about whether it was worth just changing to an integrated instead and of course with that idea goes just getting a pre-amp.

 

Is very odd as the guy I got the NAD 2200 off was also selling a matching NAD 1000S pre-amp - which was NAD's top pre from the 80's. But I didn't get that at the time.

 

I have this desire to minimise all the number of components needed so hoped I could get by without it....so perhaps I need to chat with him again.

 

That said the simplicity of an integrated might be better and really I'm wanting to get speakers with a high effeciency level so not sure how often I'll need the power the NAD 2200 is capable of - but I digress. Its a good point you make though.

 

[One and a half]

Affects XP and MCE (tarred with the same brush).

Vista doesn't have kmixer, uses a lot better stack, here's some light reading for you.

http://msdn.microsoft.com/en-us/library/dd370802(VS.85).aspx

 

Players like Foobar2000, J River Media centre can address the 2nd layer above the physical card (the endpoint in Windows speak) in Vista & Windows7, the Windows Audio Session API, WASAPI layer. This addressing can bypass the mixer (don't confuse this with kmixer), windows volume control, all other sounds from the computer, so you have a very clean and direct path from the application to the sound card. iTunes can't get to this layer in the current Version 8, but previous versions could by 3rd party applications. I would go to Vista Ultimate as it has the Media Centre built in.

 

I found out the hard way:

Use a DAC externally to reduce interference from the PC

 

You can use USB to the DAC, but the best you can get is 16bit/44.1kHz without drivers. With drivers you can go higher, but maxes out at 24bit/48kHz. The limitation is the chips on the front end of the DAC these days.

Your sound card can resolve higher with the SPDIF coaxial or optical outputs right to the limit of the card, 24bit/192 or even more. Avoid the analog out of the PC, the noise coupled from the PC is horrendous, so optical is the best option there. I like coax due to distances, if it comes to that, find a media converter from optical to coax.

 

http://coemaudio.com.au/Sources/DACs/191/

 

Apple comps use the firewire interface which are very good = read expensive. some where along the line in here, everytime you go through the SPDIF connection you introduce timing errors, jitter. How this effects the sound is largely how you believe it makes a difference or it's the end of the world. It is with good fortune that HDMI 1.4 (released a few days ago ) now includes another audio channel for feedback, so in theory jitter won't be an issue anymore since clock data can go both ways.

 

SNR - any good sound card or DAC is well over the -110db these days. That's for analog, but we use digital from the PC right to the DAC, so this is a non event, so rest easy.

 

Volume control

How well do you want to protect your tweeters? Anything can happen, some unexpected blip, or noise you didn't expect goes at full volume to the power amp with 100% gain, gonna blow your tweeters in no time. Better to have some control with a big knob than some mouse you need to navigate with. A few DACS come with a pre amp in them so you have flexibility here.

 

 

 

[Audio_ELF]

One and a Half said...

"You can use USB to the DAC, but the best you can get is 16bit/44.1kHz without drivers. With drivers you can go higher, but maxes out at 24bit/48kHz. The limitation is the chips on the front end of the DAC these days."

Even without drivers, there are DACs and USB to SPDIF interfaces available that do 24/96. Not as common as the 16/48 devices but they are available.

 

Having said that - the original poster stated he was only interested in CD quality so that limitation is probably not a worry for him.

 

[Nikko]

One and a half,

 

Thanks for your great reply!

 

You stated,"Avoid the analog out of the PC, the noise coupled from the PC is horrendous, so optical is the best option there. I like coax due to distances, if it comes to that, find a media converter from optical to coax"

 

Can I ask what you were using when you got all this EMI/RF noise? I'm guessing an unshielded soundcard or just onboard soundchip? I know the static/noise is horrible on many of these and thats always been the main reason people have frowned on internal sound processing solutions - seems the Xonar STX may be different as they've put a lot of effort into making sure this age old problem is neutralised.

 

Do you feel this is unlikely and regardless EMI/RF noise would still be a factor?

 

[Tonto]

If you were worried about the KMixer in media centre you can get an ASIO plugin for Windows Media Player as that is what Media Centre uses to play back music anyway.

I had a good go with Media Centre in the weekend and it is excellent-I don't know why more is said of it. It has me seriously changing the direction of how I want to develop my system.

In terms of speakers/amp I recommned my setup of ADM9.1s (they do great on movies too) although abit pricy if you already have a poweramp. Maybe a good DAC/Pre to your poweramp would be the go

 

[Nikko]

Hi Tonto,

 

Thanks for the reply.

 

What an interesting idea - ASIO with WMP - as I looked into that a while back and no ASIO support existed - so I'd thought I'd either have to move to Media Portal or minimise out of the MCE 2005 interface to use. But you're right there is a new project that seems to support it - looks like the usual few glitches but might be ok.

 

Here it is for folks interested: http://sourceforge.net/projects/asiowmpplg/

 

Though obviously thats really finer detail oriented and I need to figure out the macro stuff like the DAC/speakers/Amp.

 

Thanks for the tip......I was thinking of an external DAC that also has a volume control but these are rare enough as is and to get one with USB input as well is VERY VERY hard...usually $US1000+!

 

I'm thinking perhaps the power amp I have is just too much for me anyway - I don't see myself needing 600w x2 into 4ohms very often! So might have to ebay it. Kinda sad is is meant to be one of the greatest power amps ever made.

 

Got to take my time as the economic conditions are making for great buying here but you do have to be patient - rather than trying to sort an entire system in a few days as I seem to invariably do.

 

[Audio_ELF]

Nikko said... "I'm thinking perhaps the power amp I have is just too much for me anyway - I don't see myself needing 600w x2 into 4ohms very often! So might have to ebay it. Kinda sad is is meant to be one of the greatest power amps ever made."

Because it's to powerful is a bad reason to get rid of a power amp IMO. Remember you are more likely to damage speakers with a low powered amp driven into clipping than with a high powered amp.

 

Eloise

 

[One and a half]

I see that the poster has 44.1 files, that's cool, have no problems with that. My own collection is 99% 44.1 ALAC. If the poster reads this forum more, they will find that higher res files do exist and perhaps worth a listen one day. I'm just future proofing to a degree. With so many sample rates in audio, it's hard to keep up with at times.

 

Cheers,

 

[One and a half]

I use an Asus notebook. The EMC noise comes from two places :

 

a) the brick power supply, (60-0-60V/18.5V)

b) the internal power supply of the computer running on batteries

 

Both induce noise into the analog, it's so bad, twittering chipmunks is very audible and makes a mess I tried a few cables, with no luck, the 3.5mm jack limits your choices. I can hear very clearly mouse movement and window movement on headphones, directly plugged into the analog audio out running on the mains or batteries. So I guess it was a wise move for the manufacturer to provide an optical out for this reason. I don't hear any of the noise using a DAC with optical or USB.

 

I would hope an external sound card would be immune from noise, since it's primary use is away from the PC innards and susceptible to other kinds of EMI. More the reason to go for an External DAC.

 

 

[One and a half]

leave it on for a day every six months to keep the capacitors working, then switch it off for storage if you don't need it. An amp like that will always come in handy, even for testing, 2nd bedroom, garage....all sorts of reasons. Classic amps will last a long time, mine hasn't failed, sounds as good as when I bought it 22 years ago.

 

*They don't build amps like they used to*