Yes. Extra current is nice to have. Means the supply will not get as hot.

You will need something closer to 1.4 amps.

FYI - I have added a new $159 wood panel option, which I believe makes the TUBA look much nicer. Panels can be purchased separately for those of you who would like to upgrade the TUBA you already own. Wood also fits TRUMPET MC.

Tuba works very well with these. But it's not really that expensive, so easy to overlook...

My TUBA does not have a preamp, as input signal goes straight to output tube. Just enough gain to make it work. It does have volume control. I would suggest that whatever amplifier you choose, just set gain to maximum and leave it there, which should offer least distortion and noise.

All tubes glow at different brightnesses. It's a matter of how much excess filament gets exposed outside of cathode sleeve. Tubes are built by hand. Take a closer inspection and you will find plenty of differences. Some brands are known to be brighter than others. In the TUBA amplifier...

Tubes are oriented 180 degrees apart in rotation, in order to optimize internal mirrored symmetry. If you view from another angle the result may change... As far as gain - that is entirely dependent upon source components - some DACs are louder than others.

Somebody sent me a pair of Telefunken, which I am using now. Great detail with super wide soundstage. Not too different from the Mullard 7189. Swapped out a Grado Opus3 for my worn Dynavector, so bass is really filled out. Going to try a re-tip of my Dyna with an Ogura 3/30 line contact...

Those vents are not needed for cooling. Mostly decorative. I designed the chassis such that I can re-use it for other products, in which case a future amplifier might just require that extra cooling. Next up is a matching phonostage... :)

Yes, I did this on purpose. I do NOT want to be fabricating all these wood panels by hand. That's not my thing. You can probably do a better job. Just buy 2 feet of 1x4 (standard North American size) of your favorite tree. Cut to 10.5" each. Sand like crazy. Use #6 wood screws to attach...

Hmmm. Does it do the same with LO output? "Hollow" is an indication one channel is out of phase...

That's a bit sloppy, and ends up lowering heater voltage by the same percentage. Try to keep it within 5% or better.

No, it was a last minute addition, sort of sloppy implementation. Sound is better and more pure without.

I don't make any money selling kits! No can pay rent. The kits (when available) have mostly been used for advertising purposes; getting the word out, generating some buzz. I'm doing it again in the guitar pedal world...

Yes, headphones can stay plugged in. There are no pops or thumps during power up/down.

Sounds like a missing ground (Earth) connection.

This should drive LCD3 just fine: https://www.head-fi.org/threads/hagerman-audio-labs-tuba.915475/

You may want to try replacing the tube with a jumper. Might improve sonics.

I have not tried LCD-3 yet. Sundara work well, but do not get very loud. Grados go super loud (ear-splitting) as do HD600. Very loud would be DT990. According to LCD-3 specifications, they should work nicely with plenty of headroom. jh

The chassis is actually aluminum, not steel. I never use steel in audio, due to eddy currents and "smear" it can add if too close to a coil. The aluminum lets me put things where I want them, is a better conductor, and doesn't rust if paint gets chipped. Built to last, as they say. Hopefully...

Hagerman Audio Labs TUBA, $649.

Matching sets of NOS EL84 tubes today and ran across this pair of Mullards (made in Great Britain, 1975?) that were so perfectly identical their overlapping curves looked like one set...

https://positive-feedback.com/reviews/hardware-reviews/hagerman-audio-labs-tuba/

Yes, your Behringer should work just fine with those cans.

Should work fine.