"Adding circuitry" for headphone out is not a simple matter, at least not if you want a good headphone out. Could you ask him if he can derive the headphone circuit from the actual tube stage, not not just add a separate op-amp based headphone jack like Audible Illusions L1 used to do?
If he does make such a beast, lots of people at Head-Fi.org will be interested.
I'll certainly ask what's involved in the headphone out modification. I'm pretty ignorant about these things, but the correspondence I've had with him suggests that the headphone out certainly uses the tube stage. When he tried to compare the relative merits of the headphone out on his pre-amp and my current solid-state head-amp, he certainly referred to the "tubiness" of his headphone out.
My correspondence with him largely involved the QA-001. This is the bottom product in his pre-amp line, using two 6SL7 or two 6SN7 tubes, a single input and a single output (in its standard configuration). With the 6SN7 tubes, it would generate gain of around x5, with maximum output of around 5Vrms.
With the simple headphone mod (whatever it involves), the headphone output would generate only around 0.6Vrms output into my 300ohm Sennheisers. Albert wasn't sure that this would be sufficient to drive them adequately (although he suspected it would be). He suggested that he could mess around with the circuit, add an additional two 6SN7s and increase the transformer rating, and increase the headphone output to around 5Vrms into 300ohms, which would be sufficient to drive the Senns. Again, this suggests that the headphone out comes from the tube circuitry.
Moreover, whether the "standard" modification he makes to provide a headphone output involves a simple op-amp headphone jack, it certainly seems that Albert is willing to make significant changes to his designs to accommodate the needs of the customer.
I think I've changed my mind about how to proceed, though. The QA-001 is $400, and the proposed mods for the headphone out would have cost another $300. So, I think I'm likely to hold onto my current head-amp (Sugden Headmaster, which has been used for pre-amp duties up until now), and use it from a tape-out on my new pre-amp. This allows me to fool myself into believing I've saved a heap of cash, and so justify buying a pre-amp from further up Albert's line - the QA-112 (not the QA-113 that I mentioned before). The QA-112 utilises tube rectification, and comes equiped with an extra input and an extra (tape) output.
As an aside, Albert's webpage also lists several head-amps in his product line. These are generally more expensive items than I was looking for, and most are low-powered SET integrateds, rather than pre-amps.
Chad
