You have a great start with the Totems. If you're mostly interested in HT, then moving to a multichannel amp and pre/pro at this stage makes sense. If you're generally happy with your HT set up now, though, you might consider adding a nice 2-channel amp (keeping your AVR as the preamp). I'd bet that your Totems would begin to open up and sing on 2-channel material with just that change alone. You could then reassess and decide whether you want to add in a 3-channel amp for your rear and center speakers. There are a lot of great options for high quality, $800-1500 2-channel amps. Many folks here on AudiogoN use 2-channel pre-amps with home theater pass through options. You may want to look into that if you haven't considered.
e
e