Maybe someone can help identify this?

Hi,

I was looking for a headphone amp the other day and picked this up on the 'Bay. In theory, it's also a pre-amp. But, I don't know what it is based on, or if it is based on any design that I've seen before. And it's sooo small and fiddly that I'd hate to start playing and stuff it up. It's actually got quite a nice, fairly neutral, sound, but I barely use any of the 2 volume pots (my Audio Technica's are quite easy to drive) and it rolls off starting at around 50Hz (so there's barely anything left at 25). I guess I'd like to use more volume control (I'm currently scared to put it in my pocket) and I'd like to see if I can roll it off a bit lower down.

This is the full internal shot:

And these are close-up of the two boards.

Some of those numbers seem to be:

(on the smaller board)

476A M2405 (x2)

613

and what looks like RIAE?

(on the bigger board - for each channel)

SL6310 PSSA

6 N 100 35v

473 (x2)

243

295 (or 562 - depending on which way up you are)

I can go in with a magnifying glass to look at anything else. I'm keeping it, but I'd like to know more (and all I got was the unit, no provenance).

Thanks, Mr X.

I also located this (http://www.head-fi.org/forum/thread/240212/ebay-amp-well-worth-checking-out) thread, which seems to have Pangaea buying one based on a different op-amp (but from the same person) and kramer5150 having seen those amps previously. As it was posted in 2007, I can't follow up, and there's bugger all on any SL6310 headamps anywhere on the net' Mine was advertised as class A - which gels with the description of the SL6310 response on the eBay auction.

Sigh! Is lack of knowledge a problem when it comes to enjoyment? No. But is it frustrating? Yes, raather!