After getting the speakers, cables are next - they do reward. 10% of your systems cost to cables sounds reasonable. Get them used. You can get some here on audiogon.
You might like speakercity.com EFE speaker ($330). Nice highs you can listen for a long time. They got some good reviews.
Niles audio outdoor speakers are also nice and soft sounding with a good transparent souding tweeter.
You said you bought the Yamaha coz the salesman told you they were work horses - without being too cynical, next time please take what the audio salesmen say with a grain of salt. They have become experts at selling at our price point.
Yamahas sound pretty good especially for what you payed for them.
I would read Hifichoice.co.uk although even magazines are sometimes biased toward those companies placing ads on them. The advices here are good, and also you can chat alive on audioasylum.com Since you were a music teacher, your ears must be well developed - having heard many alive music. In the end, I would say buy what you like. That sounds so simple, but you will be the one listening to it, so it should please you, despite what other's recommend.
I teach music too - cello and piano. Nice to see someone who has made his vocation avocation, and still loving it. I hope tobe that lucky after I retire.
I too got into this hobby not too long ago. It's tempting to keep upgrading, but I decided to enjoy my system for at least an year before upgrading, coz others have warned me about the constant upgrade bug.
It certainly is an exciting hobby. Reminds me of an artist going to a great length in search of beauty. There is a lot we can learn to tweak our system to sound better. I wouldn't open a unit without knowing safety measures first though!
Have fun... and welcome aboared.
