Note: I added in black plastic/glue from my 180W glue gun. This was to add support for the adapter and capacitors, in order to isolate vibrations and increase the longevity of the mod.
At less than $200, the S.M.S.L. sAp-10 is a hefty contender in the field of balanced headphone amplifiers. However, it relies on one JRC 5532 surface mount (SMD) op-amp. I decided to upgrade this to a DIP-8 socket, so that I could try different op-amps. To achieve this I used a special adapter that goes from SMD pads to a DIP-8 socket. While I was in there I decided to go ahead and swap out the few SMD capacitors with full-size Panasonic FM capacitors.
Having the ability to swap the op-amp is a huge sonic advantage (to anyone with spare op-amps). Going from a JRC 5532 to a Burson Audio V6 Classic or a Sparkos Labs SS3602 made a clear difference.
The handful of remaining SMD capacitors are related to the power circuitry ICs (outside of the signal path).
I haven’t yet had the time to analyze the circuit to see what configuration the op-amp is in. Op-amps can serve a variety of purposes in a circuit: amplification, voltage followers, buffers and rectifiers (to name a few configurations). Swapping in full size capacitors helped bass response/headroom and seemed to improve rejection of buzz/hum. I also believed it helped the mid-range out.
Note: The flexible lead DIP-8 socket can be purchased at Burson Audio’s website.