I used a Denon 5308... in the mid-2000s, it was here for several years actually. It was a horrible-sounding piece of crap when it came to the amplifier section. It was SO OBVIOUSLY terrible sounding compared to using its line-level outputs into any decent standalone amp(s) NOBODY could have missed it. And that was with 8-Ohm speakers. 4-Ohm speakers were made to sound dark, muffled, & gray, with high frequencies that lacked life. I currently have a Denon X8500H here (from the last model year, 2019 introduction I think, a $4000 AVR and it is INCAPABLE of revealing the full performance of ANY loudspeaker, but 4-Ohm speakers really suffer. Do you realize that "4-Ohms" doesn't mean any given 4-Ohm speaker has a linear impedance of 4-Ohms over the entire audio frequency range? Almost all 4-Ohm speakers have impedance dips that go down to 2 Ohms in one to three places in the frequency spectrum. This affects just part of the frequency range, but more current is demanded in those parts of the frequency spectrum. Do you understand that amplifier circuits do not deliver power continuously? They can't/don't produce any power at all until the instantaneous AC Power Line voltage is higher than the power supply voltage rails in the amp? If the amp's power supply voltage is 90 volts, when the AC power line is below 90 volts, the amp circuit produces NO power. The amp can only DELIVER power during parts of the AC power waveform with voltages from 90.1 volts to 172 volts (about what AC peak voltages are for nominal 117 VAC power). When the power line sine wave is in the range of 0-90 volts (or 0 to minus90 volts) the amplifier power supply stores power in the power supply capacitors. The amplifier begins producing power as the instantaneous sine wave voltage goes above 90 volts. When that happens, current RUSHES-IN to the amp at close to DOUBLE the rated current consumption. Amplifiers draw current at about DOUBLE their current rating (when driven to full power) for half of the AC Power sine wave and they create ZERO power for about half of any given AC power sine-wave cycle. When you look at the CURRENT going into an amplifier on a 'scope, you see more or less a square wave that is modulated by the music signal across the "tops" of the square waves. There are also Asian companies who make AVRs for customers who DESIGN THEIR OWN AVR either from scratch or by modifying a "stock" AVR design and having that modified AVR be sold under their potentially non-Asian brand. Asian-manufacture doesn't automatically make an AVR "Asian-brand" for purposes of my responses, because the AVR design could be English, Canadian, US, French, German and simply be BUILT over there to reduce costs. Some of those Asian factories cater to customer-designed products from the circuits to the appearance and features. Asian-designed AVRs work best with 8-Ohm speakers, and are useful with most 6-Ohm speakers. I have used top-line and mid-line AVRs from StormAudio, Denon, Marantz, Onkyo, Integra, Sony, Anthem, AudioControl, Arcam, Cambridge, NAD, Rotel, Outlaw, Pioneer, & Yamaha. And that list is just from the last 10 years, I've been doing this a long time. Current is king for 4-Ohm speakers and Asian-brand AVRs aren't concerned with current in AVRs to support 4-Ohm speakers. Period. That said, AFTER the Denon 5308, somewhere around 2010 or 2011, something happened to Asian-brand AVRs... the AMPLIFIER sections got MUCH BETTER SOUNDING, I mean night and day better-sounding. But they were still good only for 6 and 8 Ohm speakers. A NAD AVR rated at 80 watts delivered much more current to a 4-Ohm speaker than a Denon 140 w/ch AVR and the NAD AVR sounded better than the Asian-brand AVR by an obvious amount on those 4-Ohm speakers. I don't remember if the NAD AVR was made in China or not, but WHERE it was made isn't the issue, it is the DESIGN of the AVR's amp section that makes all the difference. Asian-brand "watts" are MEANINGLESS when it comes to speakers that need more current than 8 or 6 ohm speakers because the Asian brands aren't designed to deliver the current. They are only designed to TOLERATE 4-Ohm speakers without damaging the AVR. Once the current demand on the amp exceeds the amp's ability to DELIVER current to the speaker, clipping begins in the voltage domain and that clipping presents pulsating DC to the tweeters causing them to get hot... if exposed long enough, the tweeter will fail from the heat. How long is "long enough" -- I'd guess 15 seconds to 2 minutes depending on the severity of the clipping. But I've never blown up tweeters with an AVR so not sure. I have observed clipping in the analog waveform going to the speakers when using an oscilloscope, so I can always find the point where an AVR begins to give up on current pretty easily. And Asian-brands (not Asian-manufacture, but Asian-brands) are very clearly not delivering as much current as Anthem, AudioControl, NAD, Rotel, StormAudio (AVR now discontinued... it was $14,000-ish), Cambridge, or Arcam.
Indeed, people can say anything they want online. Some of us happen to know what we're talking about--I know it's rare. But I'm one of the ones who "know things" because of my background in engineering (mechanical, video, electrical, computer, and power supply), high-end audio, and home theater (I took my engineering interests and applied them to home audio and theater that turned into a hobby and a second profession). I worked on the film scanning equipment used in some of the first digital remasters of classic movies like "Snow White"... not running the equipment, but designing and testing it and leaning over image scientists' shoulders while scanned images were examined almost microscopically. Also worked on digital cinema and 3D devices for medical, oil exploration, outer space use, and other critical 3-D applications. I designed and tested power supplies and insured they met EMI/RF emission standards world-wide (which get pretty weird, and very specific). No way for you to know that, of course. Not sure how else to explain how I know what I know.
