Well not always true but certainly true of modern and midrange AVR units.
http://www.cnet.com/news/how-can-30-year-old-receivers-sound-better-than-new-ones/
I been saying and thinking this for a couple years and glad to see I'm not alone.
My 10+ year old Harman Kardon AVR525 still sounds better than the subsequent Onkyo, Onkyo again, Denon, and Yamaha amps I replaced it with. It doesn't do DTS HD or Dolby True, but play a CD and it craps on them. It was cheaper 12 years ago than my current Denon 3312 cost me two years ago too.
Gttenberg is a buffoon who believes in most of the audiophile ju-ju out there.
I've repaired or worked on quite a few AVRs and the signal path for most of them is digital in -> DSP -> DAC -> poweramps. Analogue sources typically go into a selector chip/ADC combined, then to the DSP. All processing is done in the digital domain. The signal path is shorter than most old receivers and much simpler.
ICs improve over time and there is very little there that needs improving because typically it's been essentially perfect, ie inaudible for a long time and there isn't much there anyway. Tuners have been good for decades at least for the typical poor quality of signal most stations put out these days.
People have made arguments that discrete poweramps are better than IC units, but based on my experience, I call BS on that. Except for very few units from a decade or more ago, used within their range, they are by and large excellent. Does anyone remember the fuss about the
47 Labs amps from around Y2000 and all the gushing at went on in the press about how good they sounded? It's an LM3875 in the most basic schematic from the datasheet. Also designers get around the difficult thermal requirements by keeping the output devices off the main IC. You can take an $11ish
LME49830 addd a few passives and the output devices and driver and build a 500W poweramp that looks to most people like a 'chip' amp and have something that equals or betters most discrete designs. It's simple and cheap to build an amp of about 100W (around the o/p of most AVRs) with noise and distortion too low to be audible and measure in a way that the designer of those old receivers shown the the article would have killed for. It's nostalgia driving what they're saying as having been inside a lot of those receivers, they are simply not all that great. I could better all the analogue line levels stages of those old discrete units with an NE5534 (a >30yo design) let alone with something more recent like the LME49720. I've already described how the power amp stages could be done with the LME49830.
Power supplies have gotten smaller, true, but I've still yet to see any real evidence that it's going to be awful sounding as a consequence. The magazine tests that people quote from time to time that show power dropping all channels driven are of little relevance: how often is full power required on all channels, in phase simultaneously? Very, very rarely if ever from more than a fraction of a second with actual program content. You'll just lose a bit of level which is quite hard to detect under short transient conditions. If you hear distortion on transients because of this, you need to step up to something bigger is all, or add an L/R external poweramp.
ADCs/DACs have long been transparent enough and the SOTA 24 bit units of a few years ago have been recycled into the multichannel ICs used in receivers today.
All the other digital features like Bluetooth or streaming are commodity chips with the processing in the digital domain.
I love analogue design and it was my employment for many years and has been my hobby for 30. But I have no nostalgia for most old gear and have designed/repaired/measured and tested a lot over the years so I don't buy the hypothesis that modern AVRs are crap and old receivers are good because my training and experience tells me otherwise. Oh, and especially considering the source of the article, I wouldn't give it much credence anyway. The only way my old Marantz 2285B receiver betters my newish Onkyo is aesthetics. The Marantz is a beautiful piece of industrial design and the Onkyo a drab black box.