Tube Integrated with deep bass

Aronov LS-960I has been a tube integrated bass performance champion in a reasonable used price range, $1200 range.
Although manufacturer no longer active, it has a straightforward design that any tube repair facility can work on.
Not vintage, and sold in the 21st century.
The overall sound is very natural, or realistically musical, not simply killer bass.

Audio Note Soro SE has amazing bass

I am selling mine but it makes no difference on my opinion - awesome bass for tubes or solid state

I was impressed with my McIntosh MA2275 integrated once I installed Siemens ECC801S's in the 12AT7 slots. The Siemens, IMO, are noted for their tight, heavy bass.

FWIW, I checked out that Graaf integrated Glide3 mentioned and I wouldn't even consider for a moment buying from a seller with that history.

I have a Cayin A-50T and it has some pretty decent base.