Quick introduction: I recently sold my Emu 1212M (modded: I bridged the coupling caps, replaced others in the analog section with blackgates) and now have the Emu 0404 USB. It sounds ok for the price (or compared to decent CD players like Marantz CD67), but I don't like it as much as the modded 1212M. The 0404 can sound a bit harsh at times (especially symbals on drums and vocals sometimes have a bit too much energy in the "s" region and have a bit of a "sharp" quality). I know this sounds weird because the frequency response and other specs are quite flawless but to my ears, this sort of sounds like the original 1212M. The modding brought "life" to the sound and maybe the 0404 is just an unpolished diamond...
I'm hoping you guys can help me out a bit in trying to squeeze more out of this little gem. The 0404 uses AK4396 as the da-converter and I'm sure many of you have heard the buzz around this one (many regard the AK chips as the best converters and the 4396 is definately from the higher end of AK chips).
So, let me give you a short tour.
On the left side of the potentiometer is the da-chip (half visible). On the right side of the chip are the R+, R-, L+, L- rails going in to the 4 capacitors. After the capacitors are two JRC 2068 opamps. On the left side of the caps is the headphone stuff (let's not go there).
On the right side of the potentiometer the output stage continues. Two 5532 opamps next. The big plastic thingies are the balanced outputs.
So what I've done so far? I replaced the four caps (coupling?) with Elna Silnic II as I had some in my drawer. Did the sound change? Don't know. At first I couldn't hear a difference but after keeping the unit on for 24h I got the feeling that maybe the sound is not as harsh but then again, maybe it's just my brain playing tricks on me.
What would you guys/gals suggest I could try next? Can you find muting transistors I could remove or any idea if I could bridge the coupling caps etc? I have Auricaps in the input of my amp so DC is not a big concern.
For reference:
AK4396 datasheet (last pages include reference circuitry and I believe it's very close to what the Emu has)
Some nice photos of the Emu 0404 USB PCB
Lots of PCB pics