My suggestions would be:
-Meze 99 Classics
-HiFi Man 400i
-Audioquest Nighthawk or Nightowl (If you can find them, discontinued)
I use a Synthesis 41DC+ integrated tube amp (ECL82/6BM8 in a Single Ended 2W class A), source is USB from a PC usually running Tidal using CD Lossless quality. My headphones are the Audeze LCD-2. I am very happy with this arrangement. It's clear and huge, and has a ton of bass for the clarity. I also run low capacitance litz cables and an IsoTek Evo 3 power conditioner.
@youngerd This is not yet released widely (next month) but the $2K RAAL CA-1a will likely be incredible on your gear. I am using it on a $500 Schitt Jotunheim R and it is rather good. On my $7K RAAL VM-1a (tube headphone amp for ONLY the RAAL SR1a and CA-1a) we are approaching the best of the best in headphones and maybe even 2-channel. In 6 months or so, you may be able to get a used one for $1000. It is not a pretty headphone.
There is an $500 interface box that allows any headphone amp to play the CA-1a or SR1a. I never tried it. So, your tube amp should sound good. I use a Benchmark DAC3B ($1700) and a Topping D90LE DAC ($719) and they are amazing with either of my amps.
I have a 'better' DAC, Musetec 005, but I have not given it much of a spin yet on the headphones since the cheaper DACs are really working for me.
I am listening to the CA-1a and VM-1a in PENTODE mode and I think it will be a long night of hard rock.