[SoundWalker]

Well I went back and redid the gain setup on the pa2v2 using my hd 555. No success.
 
I'm now convinced the pa2v2 is simply not good enough for a pair of headphones of 55 ohm impedance and up. You lose huge amounts of sound definition and quality. The sound is simply gutted.
 
I've found the max impedance for the pa2v2 is a 32 ohm headphone after testing it with all my gear.
 
 
I'm getting the impression lots of people are completely oblivious to the true potential of their high-quality headphones.

 

[rroseperry]

Have you tried emailing Gary about this?

 

[SoundWalker]

Quote:

Have you tried emailing Gary about this?

No I haven't. I guess it wouldn't hurt to contact him and see what he thinks. I'll write him an email.

 

[Roller]

 
Quote:

Well I went back and redid the gain setup on the pa2v2 using my hd 555. No success.
 
I'm now convinced the pa2v2 is simply not good enough for a pair of headphones of 55 ohm impedance and up. You lose huge amounts of sound definition and quality. The sound is simply gutted.
 
I've found the max impedance for the pa2v2 is a 32 ohm headphone after testing it with all my gear.
 
 

I'm getting the impression lots of people are completely oblivious to the true potential of their high-quality headphones.

 
Well, my PA2V2 made wonders for all my gear, though while the Technics RP-F290 had little to no improvement for some reason, both the Philips SHP2000 and the A&H XD-53 do gain both output and clarity by being powered from PA2V2. I didn't get the amp to listen to the headphones louder, but to feed them enough juice to make them justice. Though when adjusting gain almost near the maximum, sound does distort severely, but that's a way too high level. I've read from other threads that PA2V2 does in general need high gain settings, and in my case I agree as I have it at 60-70%
 
Have you checked your whole sound chain? Perhaps some cable might be messing that up. Also, I've had SQ issues when I first got the amp, but that was both because I had wrong gain and volume settings, as well as not having replaceable batteries inside (fundamental!). Curiously, some reported better results running on batteries alone, while others being plugged to an outlet (with the batteries inside as well). Since you got the batteries, virtually all sound issues disappeared.

 

[SoundWalker]

Quote:

 
Quote:

Well I went back and redid the gain setup on the pa2v2 using my hd 555. No success.
 
I'm now convinced the pa2v2 is simply not good enough for a pair of headphones of 55 ohm impedance and up. You lose huge amounts of sound definition and quality. The sound is simply gutted.
 
I've found the max impedance for the pa2v2 is a 32 ohm headphone after testing it with all my gear.
 
 

I'm getting the impression lots of people are completely oblivious to the true potential of their high-quality headphones.

 
Well, my PA2V2 made wonders for all my gear, though while the Technics RP-F290 had little to no improvement for some reason, both the Philips SHP2000 and the A&H XD-53 do gain both output and clarity by being powered from PA2V2. I didn't get the amp to listen to the headphones louder, but to feed them enough juice to make them justice. Though when adjusting gain almost near the maximum, sound does distort severely, but that's a way too high level. I've read from other threads that PA2V2 does in general need high gain settings, and in my case I agree as I have it at 60-70%
 
Have you checked your whole sound chain? Perhaps some cable might be messing that up. Also, I've had SQ issues when I first got the amp, but that was both because I had wrong gain and volume settings, as well as not having replaceable batteries inside (fundamental!). Curiously, some reported better results running on batteries alone, while others being plugged to an outlet (with the batteries inside as well). Since you got the batteries, virtually all sound issues disappeared.

Hi Roller,
 
Thanks for your reply. All your headphones fall into the 32 to 36 ohm range according to a little google search I just did. This is in line with my theory - though I don't have a 36 ohm headphone (only 44 ohm) - that the pa2v2 is simply not cut out for a headphone of any higher impedance.
 
I have started from the lowest gain setting all the way to the top. At about 70% the sound quality starts to degrade and gets very muddy and distorted.
 
My pa2v2 is plugged into the wall and has a pair of 2500 mAh NiMH rechargeable batters in them. The batteries have been drained and fully recharged recently and seem to be in working order.
 
I will give the cabling a check to see if there are any issues.

 

[Roller]

Could you post your audio gear specs? You have to take in account through what the sound goes through, and set individual volumes accordingly.
Also, Gary is a great guy, if you haven't mailed him yet, you should do it as soon as possible.

 

[SoundWalker]

Quote:

Could you post your audio gear specs? You have to take in account through what the sound goes through, and set individual volumes accordingly.
Also, Gary is a great guy, if you haven't mailed him yet, you should do it as soon as possible.

Sure thing.
 
My Audio sources are a MacBook Pro and an IPhone 3GS through their headphone jacks. I use a both a 2 and 5 ft 3.5 cable to the pa2v2 input jack. I then plug my headphones into the output jack of the pa2v2. I'm using a Grado conversion wire to bring my HD 555 connection down to 3.5mm.
 
I set my devices at between 70 and 85% volume.
 
I also have a dock for my IPhone which gets the sound signal directly from the phone's data jack. Same result.

 

[Roller]

I was going to advise on getting a LOD, but you already took care of it. AFAIK, if you're using an amp, the source volume should be set to maximum, and the volume adjusted afterwards through the amp's knob.
I'm torn between suspecting of your particular set of HD555's or the amp itself.

 

[Eric_C]

It could be a sound sig + impedance matching issue. I don't have equipment to measure the output impedance of the PA2V2, so this is just conjecture based on the concept of impedance matching as discussed on this forum.
 
In terms of actual experience, I've found the PA2V2 plays happily with my HD 25-1. As you may know, the HD 25 exhibits a relatively bright sound signature (both relative to the rest of Sennheiser's line up, and against the majority of other headphones), and it has an impedance of 70 ohms. The PA2V2's slightly warm colouration thus makes the sound more euphonic, and although I cannot isolate impedance matching as an additional factor, it is certainly quite possible that plays a part too. In any case, the 70 ohm impedance of the headphones do not seem to prevent the amp from driving them without distortion.
 
The 555 is already warm-sounding, isn't it?

 

[mitchlol7]

rechargable battery, personal touch and free support for (his) life had me sold.

 

[SoundWalker]

Quote:

rechargable battery, personal touch and free support for (his) life had me sold.

 
Yep that's pretty much my story.
 
Like others have already stated, he's an awesome guy and has amazing service.
 
I just emailed him about the struggle I'm having powering my HD 555 headphones with the pa2v2 and he immediately offered to take a look at them and repair them if need be. Simply awesome.

 

[mrbrad]

I have HD595s and the PA2V2, and they work just find. The specs on the 555 and 595 are identical.

 

[markdam]

Quote:

cant wait to see what gary says about this and solving the mystery! post as soon as you find out  soundwalker!
 
 
 
Originally Posted by SoundWalker /img/forum/go_quote.gif


 
Quote:

rechargable battery, personal touch and free support for (his) life had me sold.

 
Yep that's pretty much my story.
 
Like others have already stated, he's an awesome guy and has amazing service.
 
I just emailed him about the struggle I'm having powering my HD 555 headphones with the pa2v2 and he immediately offered to take a look at them and repair them if need be. Simply awesome.

 

[rataplan]

great little amp, i tried it out for about a half hour at bay bloor radio in toronto. i know gary is local, but i "needed" them today ... so i was happy to bay bloor's $20 mark up, 79.99.
 
i'm noticing much more low range definition and a ton of "slam," just what i wanted. my grado 325is have never sounded better!
 
thanks gary for making such a great and affordable product, will definitely recommend it.

 

[jononku]

Quote:

great little amp, i tried it out for about a half hour at bay bloor radio in toronto. i know gary is local, but i "needed" them today ... so i was happy to bay bloor's $20 mark up, 79.99.
 
i'm noticing much more low range definition and a ton of "slam," just what i wanted. my grado 325is have never sounded better!
 
thanks gary for making such a great and affordable product, will definitely recommend it.

I've had mine for a few months now and am extremely pleased.  I got mine for less, but would have gladly paid double.  I've now recommended this amp to 4 others and counting, all happy customers.