Hello all! I have an Antique Sound Lab MG-Head DT headphone amplifier. It
has 2 6BQ5 tubes of an unknown brand and a single JJ ECC83 tube. I use it
almost exclusively for classical music listening. Not much Mozart but alot
of the heavier orchestral stuff like Bruckner, Vaughan Williams and
Shostakovich. I'd like to start tube rolling with this thing to see how I
can better the sound. Any suggestions on replacement/alternate tubes and
where to find them?

Larry