Switching Between Headphone Amps

[Jeff_N]

Hi,

 

I have a Vincent KHV-1 hybrid headphone amp fed by a Yggdrasil DAC. I recently bought a kinda crappy Massdrop Koss ESP/95X electrostatic pair of headphones with associated energizer, because I wanted to see what ES headphones sounded like.

 

The Yggdrasil has two sets of unbalanced RCA outputs, but one set goes to my regular speakers amp. The other set goes to the Vincent, so when I want to listen to the Koss headphones I swap around the RCA cables. None of my amps have balanced inputs, so I can't use the Yggdrasil's balanced outputs.

 

Is something like this https://www.amazon.com/EZ-ADA4-Stereo-Audio-Distribution-Amplifier/dp/B002T5VNIW between the DAC and the two headphone amps the best solution to switch back and forth between the two? Or should I stop whining and continue swapping the cables? Thanks for looking.

 

Jeff

[PAR]

You don't need an amplifier stage ( powered switch) between the DAC output and the headphone amp input. Otherwise you are feeding one amp ( which if cheap is not going to be too great) into another amp. You just need an audio switch box with two outlets.

 

Unfortunately using a switch in this role has negative aspects ; You need three sets of interconnects, the switch itself can cause noise/distortion by making a poor electrical contact. The switch can raise the effective output impedance of the DAC as seen by the input of the headphone amp.

 

I would not want to accept the sound quality penalty of using a switch and I would prefer to plug and unplug the headphone amp chosen at any given time. However you may rate the convenience of a switch higher than the potential loss of sound quality. Only you can judge.

 

 

[sandyk]

4 hours ago, PAR said:

You don't need an amplifier stage ( powered switch) between the DAC output and the headphone amp input. Otherwise you are feeding one amp ( which if cheap is not going to be too great) into another amp. You just need an audio switch box with two outlets.

 

 Agreed. Adding another amplifier is going to degrade the SQ coming from the DAC. For best results, the audio switch box should be as close as possible to the output terminals of the DAC, and it's input cable should also be as short as possible.

If  this is done there should be very little noticeable degradation compared with just swapping cables.

 In fact, a DIY person could very easily make up a simple and inexpensive switch box in a small aluminium case.

[audiobomber]

18 hours ago, Jeff_N said:

Is something like this https://www.amazon.com/EZ-ADA4-Stereo-Audio-Distribution-Amplifier/dp/B002T5VNIW between the DAC and the two headphone amps the best solution to switch back and forth between the two?

 

I understand the skeptical responses from others in this thread, but I think what you want to do is reasonable and feasible, as long as it's done well. 

 

I was unwilling to compromise the single pair of RCA outputs feeding my monoblocks from my DAC/Pre, which left a single pair of XLR outputs for both my sub crossover and headphone amp. After considerable research, I bought a Nobsound NS-05P (also available on Amazon):

https://www.doukaudio.com/douk-audio-fully-balanced-passive-preamplifier-pre-amp-xlr-rca-volume-controller-p0077.html

 

I connected the XLR outs from my DAC to the Nobsound. I set the Nobsound pot at top dead center and never touch it. I set my dual sub level controls for proper balance and never touch them. The Nobsound switches between my sub crossover on RCA and headphone amp on XLR.

 

Although there must be some sort of sonic effect from using the Nobsound, I don't notice it, and have not bothered to try and suss it out. My headphone amp is a Hafler HA15, connected to the Nobsound via 2' XLR cable, driving Grado GH4 headphones. 

 

In your case, the NS-05P would convert the DAC's XLR outs to RCA to feed a headphone amp. This allows the other headphone amp to have a dedicated RCA feed directly from the Yiggy.

 

Here's a subjective review of the NS-05P:

https://forum.audiogon.com/discussions/review-nobsound-mini-fully-balanced-single-ended-passive-pre-amplifi

 

Here's a technical review, comparing it to a 10X more expensive Goldpoint passive unit:

https://superbestaudiofriends.org/index.php?threads/goldpoint-sa2x-nobsound-ns-05p-passive-attenuator-comparison-technical-measurements.7324/

Conclusion
When used with at least 20 dB attenuation and very short, low capacitance cables the Nobsound NS-05P will come close to the performance of Goldpoint SA1X.

[Jeff_N]

Thanks to all you guys for your help. I'm gonna give the little Nobsound switch box a try. For sixty bucks, if it degrades the sound, I'll just throw it in my gadget drawer and go back to swapping the cables.

[audiobomber]

As mentioned in the technical review, it is important to reduce the level of the Nobsound by at least 20dB, and use a short, low capacitance interconnect between it and the headphone amp. Will be interested to hear your impressions.

[Jeff_N]

Here's the conclusion. I stupidly got the Nobsound switch box without noticing it has a pair of balanced and a pair of unbalanced inputs, and a pair of balanced and a pair of unbalanced outputs. Both of my headphone amps have only unbalanced inputs, so I can't use the box. 

 

Anyway over time breaking in and listening to the Koss ES headphones, I've decided they sound like crap compared to my Sennheiser HD600 and HiFiMan HE400I, so I'll probably give the Kosses away or throw them in a drawer with the switch box.

[audiobomber]

2 hours ago, Jeff_N said:

Here's the conclusion. I stupidly got the Nobsound switch box without noticing it has a pair of balanced and a pair of unbalanced inputs, and a pair of balanced and a pair of unbalanced outputs. Both of my headphone amps have only unbalanced inputs, so I can't use the box. 

I don't understand the problem. Your DAC has two pairs of balanced and one pair of unbalanced outputs.

- RCA outs to your speaker amp

- RCA outs to your best headphone amp

- XLR out to the Nobsound, then RCA from the Nobsound to the second headphone amp.

[Jeff_N]

1 hour ago, audiobomber said:

I don't understand the problem. Your DAC has two pairs of balanced and one pair of unbalanced outputs.

- RCA outs to your speaker amp

- RCA outs to your best headphone amp

- XLR out to the Nobsound, then RCA from the Nobsound to the second headphone amp.

Okay so I'm even dumber than I thought. For some reason I got it into my head that this was a switch box, so I needed to be able to switch back and forth using it. I've now hooked it up as you suggested and it works fine. Thanks audiobomber and please don't tell anyone about this.

[audiobomber]

2 hours ago, Jeff_N said:

Okay so I'm even dumber than I thought. For some reason I got it into my head that this was a switch box, so I needed to be able to switch back and forth using it. I've now hooked it up as you suggested and it works fine. Thanks audiobomber and please don't tell anyone about this.

No problem, my lips are sealed. 😉

I'm still interested in hearing your opinion of the sound, or lack thereof, with the passive preamp ahead of your headphone amp. 

[bobbmd]

@Jeff_N (and maybe @audiobomber) if you spent the $$$ for the Yggdrasil as I did why not get the Ragnarok 2 amp(just the amp with 3 RCA inputs) which in my opinion is one 'schiitload' of a headphone amp and allows you to listen to both headphones and speakers together or separately and while you are at it with Koss's in the drawer try Sennheiser HD 598s and RS-195 wireless.

[bluesman]

On 11/20/2019 at 5:33 PM, Jeff_N said:

I recently bought a kinda crappy Massdrop Koss ESP/95X electrostatic pair of headphones with associated energizer, because I wanted to see what ES headphones sounded like.

Please forgive what may simply be my naïveté, but buying "kinda crappy" ES headphones to see how electrostatic 'phones sound is like buying a Fiat 500e to find out how an electric car drives.  If you're used to a BMW, you're bound to find anything short of a Tesla to be a disappointment.

 

Your current reference standards - all very fine pieces - include a $3500 streamer, a $1000 Vincent and a $2500 DAC (although you don't tell us what your current 'phones are).  The ESP95X is a pretty good set of cans, but the basic design is almost 30 years old, the build quality is pretty flimsy, and the amp that comes with it is marginal at best.  These will simply not let you experience the amazing potential of great electrostatics.  For example, the Stax 007s are fantastic, and the 009s are even better - but I'm too cheap to buy them 😁  For me, "even" the HiFiMan Jade II is a far better example of what electrostatics can do than those Koss, although their bass is a bit shy of what Stax and others in that league offer.

 

If you want to find out what makes electrostatics stand out, you need to go to a dealer and audition some good ones through a good amp - most ES phones today can be driven by most of the better ES amplifiers.  I drove my Stax SRX IIIs with a dedicated, well modded Marantz 8b for years back before the box that came with them (SRD-7 at the time) was also an amplifier.  If you like the immediacy, transparency, midrange detail, staging etc that you hear, and you can live with a bit of glare or stridency and without earth shaking bass, 'phones like your Koss are very nice for classical and small group jazz except for the lack of realistic weight on the bass, whether electric or acoustic.  But if your goal is to find out what all the fuss is about regarding electrostatic 'phones, "kinda crappy" ones will not fully educate you and great ones will astound you.

[Jeff_N]

You're right Bluesman, but the Koss got a bunch of glowing reviews, so I thought I'd give them a shot. I guess I shouldn't have put so much stock in the reviews. 

 

I was tempted by the Black Friday deal on the Jade II, but after my experience with the Koss I couldn't pull the trigger.

 

I'm going to CanJam NYC in February, so I'll try to listen to some ES phones then.

[audiobomber]

I heard Stax (007 and 009 I believe) through very expensive SS and tube amps at the 2019 Toronto Audiofest. I wouldn't discourage anyone from trying them, but the sound is definitely not for me. PRaT was very poor, and that is my main criterion. They made the music sound boring.

[Jeff_N]

On 12/8/2019 at 1:37 PM, audiobomber said:

No problem, my lips are sealed. 😉

I'm still interested in hearing your opinion of the sound, or lack thereof, with the passive preamp ahead of your headphone amp. 

My admittedly non-golden ears detect no diminution in sound quality with the little switch box in the middle.