Thanks very much. Talisman's specs seem a bit cryptic. The manual for the T33H on their website isn't working but here is the manual for the T35H (same except with preamp): http://www.talisman-audio.com/documents/english/manual/t35hp_aad850b.pdf. That says 'Output power: Over 150 mW on 30 to 600 ohms headset in A Class' but it also says 'Output Level: Over 7 Vrms on 30 to 600 ohms headset'. As I understand the maths, if it was really outputting 7 Vrms over 30 ohms, the power would be substantially higher than 150 mW (about 1.5 W). So either I'm reading or understanding this wrong, the output level spec is wrong (or misleading), or the output power spec is very conservative. It may be best to contact them to clarify. In any case, as you say, it's something I'll likely have to try myself.