I've owned many many receivers over the years and, in general, I'm not impressed with their sound quality. Yeah, that would be the whole bunch...
Currently, I have a 5.1-channel Oynko with 140 WPC and a few Denon 5.1 receivers, 1 Denon receiver has 105 WPC. The sound quality of the Oynko just plane stinks and really loud levels can't be achieved - ever. I think the published Oynko receiver power ratings are very suspect or their maybe the pre-amp is not designed to drive the power amps very loud. The sound quality of the Denon receivers is OK, but, in general, the power levels are not sufficient for my installations.
With a couple of minor acceptions, my speakers in all installations in the house and garage are typically JBL 2225, 2425, 2405. I love the sound quality at both low and high levels and they are reasonably efficient and, generally, they can take some abuse with ease. I also have several sub-powered 18" JBL speakers, which are really great.
In one TV room experiment about 3 years ago, I connected only two JBL speakers to the Oynko and because the sound was so disappointing, I connected the Oynko pre-amp outputs to an Adcom 555 power amplifier with 200WPC. As time went on, I added two rear speakers and a center speaker, a couple of powered sub-woofers and these newer additions for the rear and center channels were driven only off the Oynko receiver. Several years ago, the Adcom power amp was moved to perform different service in another system and currently, all the that systems 5 speakers are driven from the Oynko receiver only.
My experience with 5 channel systems is that they are annoying to balance the volume levels, especially when non-music sources sound better on stereo only and having to switch to multi-channel system and to re-balance for music material over and over again. I assume this is another disadvantage for using only one external power amplifier.
I'm currently weighing the idea of buying a few used Adcom 555 power amplifiers for the rear channels of two systems.
Questions
1. Is it common to connect only the two front channels of a 5.1 system receiver to an external power amplifier? My recollection is that the sound is not too bad???
2. If I decided to go with all external power amps that are connected to the receiver pre-amp outputs, is it better to go with multi-channel power amps or two or three stereo power amplifiers?
3. Are there any alternatives for receiver powered ONLY systems like the Denon 5700 receiver at 140WPS? These receivers are cheap as dirt on E-bay now.
4. Are the HDMI outputs and the newer THX decoders that are on new 2016 receivers so useful when used with a satellite cable source (ATT Satelite)?
SORRY FOR THE LONG POST...