This is a review and detailed measurements of the Marantz AV8805 flagship Audio and Video Processor. It is on kind loan from a member and costs USD $4,499. If you are not familiar with this category of device, AV Processors are the heart of high-end home theaters. They provide all the input switching and processor for both audio and video and leave amplification to external devices. The latter separates them from AVRs (Audio/Video Receivers).The AV8805 is a massive box to go with its massive specs such as 13.2 channels of audio:Even though it has no amplifier, it weighs as much as AVRs which do!It has the same "porthole" design of Marantz processors, going back many years. Not much is shown on that display though. To see more and to configure the device without a display, you open the larger door in the center and you have a much larger display and a bunch of buttons replicating what is on the remote. Sadly, none of those two displays, nor the information page on the HDMI out display shows the sample rate of audio being played! I have to wonder if despite the audiophile pretences behind the marketing message, whether any audiophiles were invited to comment on its features.A larger miss for audiophiles is lack of USB input. You can use HDMI, S/PDIF, Toslink and Ethernet to stream data to it but can't use it as a USB DAC. For my testing as such, I resorted to S/PDIF and HDMI.Nicely included is XLR balanced outputs which I used exclusively for my testing. Needless to say, with so many channels, the back of the unit delights any AV marketing person with more connectors than you can count:There is Audyssey Room equalization of course which I did not have time to test.As is common with brand name products, we have full safety and regulator emissions certification which is always nice and reassuring.I only messed with the unit enough to configure it for 2-channel testing. I found the menu graphics primitive for this class device. Icons were ugly and small, lacking resolution. This is a missed opportunity to make a good impression on the customer that you have purchased a high-end product.Anyway, I leave you to read the manual or other reviews on details of its functionality, video subsystem, etc. Here, our focus is the audio datapath and engineering design within. So let's get into that. Sadly the few reviews I found of AV8805 had no such data, nor has Marantz provided any information on its own. What is passed as "specs" is just a list of connectivity and features. Sad.As mentioned, I limited my testing to balanced output. If you are getting such a processor, that should be your method of connection. I fed the unit S/PDIF signal from my Audio Precision analyzer and adjusted the output to nearly 4 volts (volume level shown on display above):I don't know if I should be happy or sad. I am happy that the SINAD (signal over noise and distortion) is not sub 90. Sad because this would be poor rating even for a $99 desktop DAC let alone a $5,000 processor. We have tier three performance of all the DACs tested so far (numbering over 100 in this table alone!):THD+N is dominated by the third harmonic which means that it will peak above the noise floor of 16 bit CD content (96 dB dynamic range). So we lack transparency there let alone for high-resolution content.Dynamic range is good:Intermodulation distortion is pretty decent with respect to noise (the downward sloping aspect of the graph) but has too much distortion as the signal gets louder:There seems to be some sign of "ESS IMD Hump" around the usual level of -35 dB. It is not as extreme but that is because of elevated noise floor.Considering that I kept the output level at 4 volts, i.e. well below max, the rising distortion is worrisome.Jitter is too busy for the eye but OK audibly:There are low-frequency jitter components hugging our main tone, rising up to -108 dB or so. Due to perceptual masking however, the main tone at 12 kHz would not allow them to be audible. Likewise the rest of the spikes would not be audible due to -120 dB level (below threshold of hearing).Multi-tone test tone shows reasonable performance:Yes, we have more "grass" at the bottom of our tones than the best DACs but hey, it could be worse!Linearity out of the blue surprises us positively:Had it stayed below -.5 dB, it would have garnered the rating of excellent from me.Next test, THD+N versus frequency was a shocker:What the heck? The moment we go past 5 kHz, the distortion+noise shoots sky high. It is off the chart literally post 10 kHz. What is going on here? We are using 90 kHz bandwidth so lots of things may be going on in ultrasonic range that is not visible here. Let's tease them out using high-resolution FFT spectrum:We now have our answer but not why. We have a tone around 34 kHz that is just -45 dB down from our main signal. If we were to run the dashboard using the same 10 kHz tone and 90 kHz bandwidth, the SINAD would drop to just 45 dB! The level of that peak fortunately is proportional to the signal. Since in real content there is not a ton of amplitude at 10 kHz and higher, practical impact is not as high but let's dig in to find out what is going on.Thinking this may be an aliasing issue, I ran my white noise test where we look at how much filtering we get at 22.05 kHz. Theory demands that we get infinite amount of signal reduction at that frequency. This is what we get instead:There is almost no filtering at 22.05 kHz! It is not until we reach almost 40 kHz that full filtering takes effect. I searched the manual for any DAC filter setting but did not find anything. This is flat out broken. I get wanting slow roll off but this smells like incorrectly programmed filter setting.Back in 2014 I tested a number of AVRs and found their HDMI performance to be much worse than their S/PDIF. Is that still the case? Let's see by running our dashboard again, this time with HDMI audio being extracted from my desktop graphics card running in 4K resolution:Ah, that is a relief. We get essentially the same performance. Then again, what we have here is limited by high harmonic distortion which is likely in the analog domain post the DAC so improvements elsewhere may not show up.Let's run the jitter test to see if that is revealed there:Performance is definitely worse with HDMI (in red). We have tons more spikes relative to S/PDIF. Fortunately once again, their levels is below audibility so not a practical concern. HDMI slaves audio to video signal so the moment you use that interface, you light up tons more circuits in the unit, resulting in more interference leaking into sensitive analog portions of the DAC chip.From pure objective performance, the Marantz AV8805 Processor cannot touch 2-channel dedicated desktop DACs which cost less than its shipping cost! With no published measurements by Marantz, nor that of any reviewer, companies are getting away releasing products that leave good bit of performance on the table. Fortunately there is nothing drastically wrong here, sans the DAC filtering. That aspect needs to be reported to Marantz as hopefully can be fixed with a firmware update.From subjective point of view, if you wrestle enough with Audyssey Room EQ, you should be able to get better in-room performance than any non-EQ DAC in a real room. Then again, you can get the same in much cheaper AVRs and processors.I would say buy the Marantz AV8805 because it has the features it has not because you think it will provide reference quality audio performance. It will not.------------As always, questions, comments, recommendations, etc. are welcome.Just collected all of my pennies to afford the nice Carne Asada we had for dinner tonight at the local restaurant. Before my pocket develops a hole, would appreciate some replenishment of those funds using: https://www.patreon.com/audiosciencereview ), or https://audiosciencereview.com/foru...eview-and-measurements.2164/page-3#post-59054 ).