Is there such a thing as tube sound in a ss?

There is no such thing as "SS" or "Tube" sound. It is simply the character of an amplifier. You get "warm & fuzzy" SS amps and "Bright" tube amps as well.

Some terms are misleading.

Your description is also a bit odd. You say you get "undefined" bass with the Classe amp but "deep tight bass" with the ARC amp? I would say its the other way round. Usually tube amps have a hard time controlling woofers during lush bass passages. This might make them sound "warm and fat".

The Classe amp could have better control over the ML speakers woofers and thus cause them to sound a bit "thin". This is simply that the bass is not as "loose" as with the tube amp. The Classe amp also might be overall bright in the treble regions.

Try auditioning a hybrid power amp or a tube pre-amp with the Classe power amp.

The Atma-sphere website has some interesting white papers on different amperage paradigms. From everything I have learned from a variety of places and experiences, I would suggest that certain things are easier with tubes than SS and vice versa, depending on what you trying to accomplish.

The best 'solid state' amp I've ever heard with MLs was actually a hybrid/FET-based amp - Counterpoint NPMs. Don't know what it is but FETs do quite well with MLs.

IMHO, my Simaudio i7 integrated brings some tubeness to the table. It's got a touch of that warmth but with the control of solid state.

/ducks, buys bulletproof body armor

Almrec,
I would take the two gentlemen posting above seriously. In my opinion they know exactly what they are talking about and have saved me a lot of words to respond (:
Happy hunting for the sound you wish for,
Detlof