I am TORN between Tube power amp and SS power amp.

rodulfo, the SET amp you mentioned raises three red flags; input impedance of 50K ohms, 9.2 wpc power, and the weight of ~25lbs. Normally the weight of a SET 300B is a good indication of the quality of the transformers which are the most critical (and expensive) component of the unit. And the 9.2 wpc will be just enough to tickle the woofers on the L100. 

If the 91dB mentioned above is the sensitivity, then all that speaker needs is 1 watt to produce 91dB sound level at 1 meter. So there's no surprise that a 12 wpc amp can and will sound loud (clear is a subjective term) enough in a moderately small room. Other factors, which one could argue that are more important, are the speaker's efficiency as well as the way its impedance behaves across its frequency spectrum. Throw a piece of content with wide dynamic range and lots of transients, something like a large orchestral western classical music content, and the weaknesses become glaringly clear. Vocals, single instrumentals, and small bands like jazz trios, etc., not so much.