Back to original question........... have ordered the Valhalla 2 in black. I'll use it for my preamp as well as headphone amp until a final decision is made on which full-blown preamp to go with. At that point the Valhalla 2 will be relegated to headphone duty.
4/3 update - Valhalla 2 has arrived and is in the system breaking in with the Senn HD650. Am quite pleased with the fit & finish of the Valhalla 2. Especially for the $349. First 2-days were pretty "blah", sonically. Also, no fan of the turn-on first/turn-off last feature to keep the "thumps" out of my speakers. But, what do you want for the money? High quality and excellent sound is all I ask.
4/6 update - Well into the 3rd day the Valhalla 2 has really come into its own. Sounds good enough that will begin some tube-rolling. GL 6922s are up first.
And, now that the Valhalla 2 has proved itself worthy of keeping, need more inputs. As the Manley Mahi amps have a quite high input sensitivity at 175mv, could use a passive switch-box, like the very nice Goldpoint SW4. However, for slightly less $$ than the Goldpoint the Schiit Saga with remote control offers either a passive mode or a tube-buffer with stepped volume control. A big plus is the Saga's 30sec turn-on delay that gets rid of the turn-on 'thump' from the Valhalla 2. A no-brainer to give the Saga a try.
Should have the Saga in a few days. Like the fact it has such low gain. Should work well with the high input sensitivity of the Manley Mahi amps.