[tayano]

I'm considering to buy an amp for my um2's,saw an ad here in the F/S-forum about an pimeta.

Specs:
Cerafince caps
Welwyn RC55 C/Y resistors
Silvered mica caps
OPA627 groundchannel
OPA637 Left/Right
BUF634 2x (for a total of six used)
Neutrik Headphone connector

I've read that opa637 have problem with gain below ~6. I will be using it with iriver h10 and I wonder if it's good,will I get sound-balance issues when listening at low gain since um2 is very sensitive ?

 

[n_maher]

If it were me I'd look for an amp configured with very low gain, probably around 2, for use with canal phones like your UM2's. You don't want any noise that your source or amp has getting any more amplification than you need. Heck, I use a PIMETA with a gain of 2 with Senn 600's and it does just fine. Unless you've got a very low power source that actually needs signal amplification I see no need for a high-gain amp.

And you're correct, the 637 is not stable at low gains, some might even say it's not stable until around 8 or so. My solution for this was just to use 627s for all 3 opamps. And if the deal on the amp is good enough you could probably buy it and pay to have it modified to better suit your needs. And there is also the possibility that it would work fine for you in it's current state.

The last thing that I would be wary of is what volume pot it has in it. I've had mixed results with low-level channel matching the Panasonic pots and had better results with the alps blue velvet pots.

HTH,

Nate