Tube amp with SS like bass

T-Bone, agreed. Talk about apples to oranges, though. The Tyler PD-15, with high impedance and bass that goes to 38Hz and are quite different than even the Tyler System II that have lower impedance and go down to 32Hz.

The question of SS-like bass is almost moot with the 38Hz PD-15...several good KT88 tube amps would do the job nicely, IMO.

However, if the Tyler Signature System with bass down to 25Hz is being considered, then bass control is more of an issue.

I am using the Butler 2250 on Dali Helicon 400s and find the bass to be very tight and fast. As far as I know the amp is under only $2k used.

Try an AVA Fetvalve 550 hybrid amp or a Blue Circle amp if you can get by with less power. Both have a very similar sonic signature that no pure ss amp can match with excellent bass.

That's as close as you're going to get. I've not heard most amps but I've never heard an SS amp that sounds like a tube amp very much including Pass.