Don't choose the Lamm phono stage unless they've changed the design. The one I used last year had inadequate gain for a LOMC like the UNIverse. In addition, the Lamm's input impedance was fixed at a rather weird forty-something ohms. That's too low for a ZYX, and for many other MC's too. The Lamm seems to have been designed for a fairly narrow, and non-typical, set of MC's.
I happen to enjoy the combination of an all tube, MM phono stage + high quality stepup transformers with infinitely adjustable loading, like those from Bent Audio. This lets me easily dial in the precise impedance that each cartridge needs to perform at its best. Since you favor tubes this is one route you might consider.
The other route is an all-tube high gain stage like the Audio Research Ref. and others like Aesthetix or Manley. I haven't heard them so I can't offer any comparisons.
I happen to enjoy the combination of an all tube, MM phono stage + high quality stepup transformers with infinitely adjustable loading, like those from Bent Audio. This lets me easily dial in the precise impedance that each cartridge needs to perform at its best. Since you favor tubes this is one route you might consider.
The other route is an all-tube high gain stage like the Audio Research Ref. and others like Aesthetix or Manley. I haven't heard them so I can't offer any comparisons.
