Need some Amp help - a little new to properly powering speakers

Your speakers are of relatively low efficiency. That's the issue, not power or quality of power. As willemj pointed out, unless you level matched the Rotel and Yamaha for your comparison, it's likely the Rotel was playing at a higher volume when you perceived the improvement.

If you want low volume dynamics, you simply need speakers of high quality and greater efficiency. 

@kosst,

The OP stated that it "sounded much clearer at lower levels." He did not say it played "louder."

The fact of the matter is that a fair comparison of amplifiers requires matched levels.

High efficiency speakers manage greater low-level dynamics for a given volume.  His original post stated that he noticed a lot of "imaging" loss at lower levels. Maybe he was referring to imaging in the true sense of the word, but I'm betting that dynamics is the more appropriate adjective. I've never had an issue with low-level imaging, but all mid-efficiency speakers I've owned struggled to produce decent dynamics under 70db, regardless of the paired amp.

 I know...I know...you'll tell me I've never owned any decent speakers and that I apparently haven't heard the Focal Arias...

@kosst,

You completely misread my post. I was speaking of low-volume dynamics. I don’t know how you confused my statement unless you simply read it too fast. This is what I said,

His original post stated that he noticed a lot of "imaging" loss at lower levels. Maybe he was referring to imaging in the true sense of the word, but I’m betting that dynamics is the more appropriate adjective. I’ve never had an issue with low-level imaging, but all mid-efficiency speakers I’ve owned struggled to produce decent dynamics under 70db

Since you mentioned LS50s, I happen to own a pair, and they, like other low efficiency speakers, have weak dynamics at low volumes. It doesn’t matter if one feeds them tube, SS, class A, or AB power, nor does high or low damping factor make a difference. They simply need a certain level of voltage to open up and that means louder volume.

Anyway, the OP subsequently confirmed what I suspected, that he was actually referring to dynamics, not detail or imaging.

What folks here seem to fail to comprehend is that many listeners want the same "jump" factor (mostly regarding bass) at low volume that they get at higher (80db+) volumes. Amp manufacturers began to compensate for this with "loudness" controls once low efficiency speakers became the norm. Then the movement toward minimalism and home theater came about. AVR manufacturers know that most will only use these products for home theater, so inclusion of a loudness control is no longer worthwhile. The boutique minimalists swear that any such control compromises the sound, and/or the BOM for the rest of the amp. That leaves one the option of using separate DSP, an EQ, or high efficiency speakers to attempt to compensate for the loss of low-level dynamics.

Any honest speaker designer will attest that high efficiency speakers produce superior dynamics at low volume. I know you don’t like to read that based on the speakers you own, but it’s the reality.

I own both high and low efficiency speakers. I don’t consider either approach inherently superior. Each approach has strengths and weaknesses.