Currently, I have Senn HD-600s and a MG Head OTL and have been messing with some tube rolling too. The problem, is that now that I have discovered the tube sound, I want it for my speaker based listening as well. So, I've been looking at tubed preamps with headphone amplifiers.

I have found some Sonic Frontier's Line 1 preamp which has a dedicated headphone amp using Burr Brown op-amps and Headrooms headphone circuitry.

Can anyone comment on this headphone amp and especially how it compares to the MG Head OTL?

Thanks for your help!

I have the Line 2, and its a very nice preamp. The headphone output sounds more like a solid state headphone amp, which isn't surprising since it uses ICs like most solid state headphone amps. It sounds decent but doesn't compete with the top tier headphone amps, either tube or solid state.