The Sonic Frontiers Line 1, 2, 3 pre-amps all have the features you want AND a high quality heaphone output jack, and yes the headphone system is driven through the tubes. Also, the SF pre-amps use the electronic system designed by Headroom for their headphone system.
I have both a Line 1 and a Line 2SE and the headphone systems are excellent IMO, but then I'm not familiar w/ your Grace unit. I do use Sennheiser 600 headphones. However, the Line series pre-amps are full size, ie not diminutive at all. I can recommend any of these SF pre-amps for both headphone and regular pre-amp use. They're very versatile-- no longer in production, but available used. Cheers. Craig
I have both a Line 1 and a Line 2SE and the headphone systems are excellent IMO, but then I'm not familiar w/ your Grace unit. I do use Sennheiser 600 headphones. However, the Line series pre-amps are full size, ie not diminutive at all. I can recommend any of these SF pre-amps for both headphone and regular pre-amp use. They're very versatile-- no longer in production, but available used. Cheers. Craig