Low level res more inherent in tubes?

I think it has alot to do with the speaker system that is matched with the amp.

Rwbadly, since you are using the same speakers with a different amp, you may have noticed considerable changes in various things.

The thing I mentioned about speakers related to using a more efficient speaker, so that the system can dig more out of the lower SPL because of the lower threshold that it takes to move the drivers in a higher efficiency speaker.

Using the same speakers with a new power amp, would not really affect that speaker efficiency issue. However, the new amp could just provide more detail. I don't know which amp you had, or have now, which you are comparing vs each other. We really would need to have more information to determine anything more than just speculation.

Many people do report that lower power tube amps do sound much more powerful(watt for watt) than SS amps do. I've read many reports from users that a good 50 watt tube amp sounds as powerful as a 200 watt SS amp. Perhaps this is what you are hearing.

Also, if your tube amp is "warmer" in the bottom end than your old SS amp was, the lower listening levels may favor the warmer sounding amp, due to the Fletcher-Munson effect of the ears being less sensitive at the frequency extremes at low listening SPL(as Newbee alluded to). This could account for low frequency details being more audible at low SPL with the new amp.

There really is not enough info to make an informed statement about what you are experiencing, except for wild guesses.

Maybe your new amp is just plain better than your old one.

A list of components and listening room description might be helpful. Including the old SS amp(s) that you are comparing to the new tube amp.

Making generalized comments without knowing the particulars involved is very difficult, and probably would lead to an incorrect conclusion.

Cool, Newbee!