Well below hifi separates: individual DACs for instance. Which don't have AV paraphenalia. That's what I mean by separates, the same as Amir means when he keeps lashing expensive AV components that measure worse than a $9 DAC-on-a-dongle.
The question I am asking is, "Are AV pre-out measurements (pre-pro or receiver) measuring well below hifi separates because of below-average engineering, or because of something intrinsic to what they are?"
Thank you for the clarification. In that case I would consider it "intrinsic" or rather, "inherent" because when Amir measures the so called DAC output SINAD on an AVR, he has to measure it at the preamp output so the signal has to go through more parts such as the HDMI interface, a LSI IC or separate Multiplexor/Switch ICs, volume control IC, and then Multiplexor/Switch IC again, a buffer OPA, or HDAM (Marantz).
Separate DACs would have some of those parts too but much simpler as they have fewer channels so the ICs used would usually have better specs than the LSI and MSI (large scale, medium scale integrated) ICs used in AVRs and AVPs and even the lower priced integrated amps such as Yamaha's A-S701, 801.
As mentioned, if you look at the the THD+N specs of the volume control ICs and the DAC ICs of D+M and Yamaha's such as:
AK4490, 4493, 4497, ES9026Pro, 9028, 9038 used in many of the DACs ASR measured, vs the AK4458, AK4490 (AVR-X8500H, A110 only) ES9006, 9026Pro (RX-A3080 main channels, CX-A5100/5200 only), factor in the degradation due to the volume control, switches and the extra HDAM buffer (Marantz only) used you will see that it is practically impossible to any of those AVRs and AVPs and many integrated amps to have measured SINAD>106 dB based on the limits of the volume control and DAC ICs alone.
Take a look of just one example:
D+M (non flag ship models) and Anthem MRX1120 (flag ship) all use the AK4458 that has SINAD 107 dB (-107 dB THD+N)typical, the volume control IC's typical SINAD for 1 kHz, 1 V is about 108 dB, each of the NJU72750 ICs used for switching again would introduce another 107-108 dB THD+N.
For comparison, the $250 SMSL SU-8 DAC has the ES9038Q2M has SINAD 120 dB, that's an extra 12 dB head start from the AVRs/AVPs mentioned above. Now if you look at the ASR measurements of the SU-8 and the AVR-X3600H, the difference is just about 12 dB!! That doesn't mean if Denon had outfitted the AVR with a 120 dB SINAD DAC it would measure as good as the SU-8, because to achieve that, Denon would have us spend a lot more on upgrading the volume control, and switching ICs, OPA for various functions as well, among many other things.
On top of that, it is easy to understand with so many more channels, video, tuner, I/Os, DSP related parts, more, and larger power supply parts etc. etc., all jammed in the one box, AVRs/AVPs/integrated amp with build in DACs bound to have more noise inherently.
It would be easier for integrated amps to catch up with the separate DACs though, by simply using better spec DAC ICs such as the the ES90X8 series or AKM's AK4497, 4499, but sadly, they wouldn't do it. The $4,000 Anthem STR has a build in DAC, but guess which IC that use, the AK4456 that has about the same specs as the Denon AVR-X3400H!! Of course they don't tell you, but thanks to bench test/reviews, they know, and they tell you:
Anthem STR Preamplifier and Power Amplifier Review - HomeTheaterHifi.com
Parasound did better, for less than half the price, you do get the ES9018K2M, that's at least better than the AK4490 used in D+M's top model AVR/AVP.
Bottom line, audible or not, if you want the best possible chance of getting the highest possible SINAD as measured, start with separates, not AVR/AVP/Integrated amps. All those can perform great and their lower measured performance will not likely be audibly worse than the best measured separates, just don't expect them to top ASR's ranking chart for separate DACs.