Any point in adding tube preamp to SS integrated?

I would be very hesitant adding the gain that a preamp might add. If you can find the input max voltage and the voltage out of the tube pre I bet it will be far in excess of the capacity if you have an amp out or a pre in option which some older integrateds do (e.g. most Sansuis c.1980). It's clearly easy to do but unlikely in the Classe.
Beside that a tube buffer is a buffer . I understand that it's main function is to give the signal source a friendly impedance not a autoformer but a lower impedance than for example the typical input inpedance a CD player meets going into the preamp. There is no tube halography doing this but your CD player will sound as good as it can depending on the what the power suplly to the buffer allows.

Now
If you have heard tubes at their best you know they are incomparable IMHO and further you know what it is you like about it.
The only way! I am convinced is to fish or cut bait- and do it - use tubes all the way.That is if you really want to hear what the tube aficionado finds so appealing then start where most err by avoiding the use a tube power amp first.
Yes it is the most critrical element in obtaining tube magic. Honest the old theory that a tube somewhere in the chain will make the system sound like a tube system is completely,and utterly false.I generally say IMHO but after years of doing everything but using a tube power amp. I finally found nirvana doing just that.
Trelja a member here and old friend told me he had known this for a long time. I was floored because he saw me waste all this time and money trying to get it.
You'll save time and stop wondering what all this tube mania is about. Try it or just borrow a tube power amp you will see.
BTW I tried all tube preamps with SS power amps and that helped but didn't really yield the tube's importance to the sonic. From day one (of this hi end business)I had a tube CD player nope not that either.One caveat if you get lousy tube amp you only get the magic "forme fruste".
I found that both tube preamp and separate tube monoblocks worked out best. I have had Nirvana with scarcely a change in over 3 years.
Good luck on your journey and don't blow the Classe or your speakers to bits

Thank you all for your help. Mechans, it sounds like you have struggled with this and I appreciate you letting me know that there is no free lunch, in that if you like the tube sound, you can't get it just by adding one tube component in the chain. I have actually put a tube buffer after a DAC in this system and it helped, but did not produce tube nirvana, which is in keeping with your experience.

Good comments by the others, with which I am in general agreement.

But fwiw I'll mention that for various reasons, on several occasions with several different pieces of equipment, I have used a preamplifier connected into a line-level input of an integrated amplifier, and I have also used two preamplifiers connected in series, ahead of a power amplifier. In no case did I have a problem with overload or excess gain.

Typically I found that setting the volume control on the integrated amplifier, or the second preamp in the chain, to around 11 or 12 o'clock would result in the volume control on the first preamp being used in a reasonable part of its range.

The specs on the CAP101 don't indicate input overload voltage, and its overall (line stage + power stage) gain of 60.5 db (at maximum volume control setting) is probably a bit higher than average, but I still think you would be ok doing that.

Also, like some of the others my experience has been that a tube power amp is the most significant factor in achieving the benefits of "tube sound," but in fairness there are a significant number of others who have expressed the opposite viewpoint in previous threads here, claiming that using a tube preamp with a solid state power amp better preserves tube-like character than the opposite combination.

Regards,
-- Al

2nd to Viridian.

IMHO, Re the probability of the addition of a pre-amp adding extra gain and creating a gain overload, consider that the VC on the CAP would attenuate the gain from the tube pre-amp just as it would any other source - the worst thing that would likely happen would be you would lose a lot of the flexibility of the VC on the CAP.

A potential mismatch could occur if the tube pre-amp has a high output impedence as many do, but considering what you are doing it might well be benign. I wouldn't let the gain issue stop me for a moment.

However, as I indicated earlier, I don't think you will get real 'tube magic' anymore with this addition than you did with your buffer (a conclusion you may already have reached). But you bend the tone provided that the pre-amp you use benefits from using tubes which have greatly varying sound (like 12AX7's) and are cheap. I mention this only because I find a lot of folks think 'tube magic' has something to do with mid-range or lower mid-range warmth, high frequency 'sparkle' and a lot of other tonal issues, as opposed to spatial, liquidity, and proper decay issues which is where I think tubes can excel and SS often falls short.

FWIW.