Opinions on my sound system please?

I doubt you will be able to hear any difference. In blind listening tests no one has been able to tell the difference between a Pioneer Receiver and a Mark Livingston power amp.not to say they do not sound different only that the differences are hard to detect... With really good speakers over time you might be able to hear a difference but it would take a while.and the differences would be slight....Your best unit is the Rotel although you may prefer the imperfect sound of another component more due to personal preference more so than quality. Better speakers might help although you may prefer the older sound of paper cone tweeters that the Bose system gives you...actually they may sound more like speakers from the 1960's giving you that nostalgic sound....another receiver to consider would be NAD although if the Rotel works I would stick with that.Mission speakers from that area sound good also Paradigm Speakers if you can find them....also Energy speakers which are still being sold today although the company has changed ownership ...they are no longer inventing new product most of the product that Energy sells was developed 10- 20 years ago. I guess Audiovox feels its better to leave well enough alone...

Well, for one thing, Bose speakers are junk. So, getting rid of the Bose speakers and getting a pair of GOOD speakers, such as from Infinity, Polk, JBL, Klipsch, etc., would improve the sound quality a lot.

The change in receivers should not have made much difference as the sonic qualities of the Yamaha and the older HK are broadly similar.

You could have the greatest receiver in the world, but pairing with bad or mediocre speakers will not allow you to enjoy the receiver's qualities.

What he said. 70/80 watts from a good class A/B amp will drive a wide range of very good speakers. You neednt use a pair of Old People's paper cone speakers with no snappy treble or mid range definition.