fmw, you think speakers have a minimal affect on the SQ of a sound system? How wrong that statement is. I do think it is great however that you are perfectly happy with with your system. If it meets your needs that is great, but their are differences between amplifiers, especially Class A tubes and Class A/B transistor amplifiers.
Take for example the Polk LSi series speakers that have been recommended, I would not drive them with a low end Teac receiver. They dip to low in impedance and are too inefficient to work well with such an amplifier. For low output applications, however, a Class A tube amplifier would power them handily taking care of any load the LSi speakers would give.
The order lain out before is pretty spot on: recording, acoustics, speakers, source, preamp, amplification, cables. Cables really mean the least and depending on the application amplification is moveable.