Is DEQX a game changer?

Jeff, yes, all of the questions you raised in your previous post seem to me to be logical and valid concerns. Although as you’ve probably seen earlier in the thread many DEQX users having very high quality systems consider the DAC function and the overall transparency of their units to be excellent.

Also, while I’m not in a position to comment on how the sonic quality of the HDP-5’s D/A converter compares to the sonic quality of its A/D converter, as an electrical engineer who has designed several A/D and D/A circuits over the years (for defense electronics), I can say that generally speaking it is a considerably greater challenge to design a good performing A/D circuit than a comparably good D/A circuit, assuming both are required to perform at similar sample rates and resolutions/bit depths.

So I wouldn’t be surprised if keeping a DEQX’s A/D converter out of the signal path would have the potential to provide greater benefit than keeping its D/A converter out of the signal path. Although, again, I’ve personally been very pleased with the transparency and overall performance of my HDP-5 with both in the signal path.

Best regards,
-- Al

I see that my recent post may have confused a few people so I will attempt to clarify.

Most of my listening is with vinyl rather than digital and I prefer a very natural analogue sound whereas (to me) a lot of digitally reproduced music has a slight glare to treble which sounds unnatural. Different DACs can either exaggerate or lessen this. As a result I’ve auditioned and used a variety of these over the years until I found something that, in my opinion was as close to the pure ’analogue’ sound I was after. That is what inputs to the HDP-5 via balanced analogue connection.

Therefore I prefer to use the balanced XLR input where digital sources (CD, FLAC etc) are already processed so in effect the processor sees everything as analogue. Processing of digital inputs to the DAC in the HDP-5 is certainly a step up from the HDP-3 - both are very good. It’s just that I am rather picky & have a setup (using the external DAC) where it is pretty difficult to tell the difference between a vinyl or digital copy of the same album. Using any digital inputs into the DEQX DAC, treble is a little more ’brittle’ (I just did a swap to make sure I could qualify this remark - the DEQX processors are so good that we are talking small degrees here & I continue to be astounded by the life-like realism that the system produces).

note: from the DEQX product overview of the HDP-5... "provides transparent analogue pass-through.......Analogue inputs utilize Cirrus Logic’s reference ‘professional’ ADC to provide absolute transparency for analogue sources such as vinyl preamps and surround receivers"....I agree with that.

For sure, in theory removing the sequence that I use (external DAC =>A/D =>D/A =>out) should benefit from reduced processing. From living with DEQX & comparative listening for over 4 years, that isn’t the case for me.

drewan77, 

Sorry if I missed it, but have you tried DEQX digital out --> external DAC --> preamp (if volume control is needed)? If so, how did that compare to the setup you are currently using ( external DAC =>A/D =>D/A =>out)? 

WARNING, I’m about to bring up the controversial subject of MQA. I have been following MQA with great interest these last couple years. I haven’t had the opportunity to hear it myself, but have read as much as possible about the technical aspects as well as subjective sound quality from likes of Stereophile, AudioStream, Digital Audio Review, The Absolute Sound, and others. I’ve been crossing my fingers for the major labels to adopt the process and for content to start streaming in (pun intended). I feel MQA could be the next big thing in hifi.

I also feel that DSP ala DEQX has major potential for improving hifi. But here’s the rub, we might not be able to have both. According to Benchmark, “MQA requires a lossless transmission system from the file source to the final D/A converter. Benign DSP processes such as a digital volume control (used in moderation) immediately defeat the MQA decoding. The same is true for digital crossovers, digital EQ, and room correction. The MQA stream will be corrupted if any of these common processes are encountered. These common forms of digital processing will shut down the MQA decoder and revert the system to a 44.1 or 48 kHz sample rate and an effective bit depth of 13 to 15 bits.” https://benchmarkmedia.com/blogs/application_notes/163302855-is-mqa-doa

I haven’t heard any hifi journalists/reviewers mention this. I’d feel more confident in the truth of this claim if it were echoed by another trusted and knowledgeable source. But it seems to make sense. If true…that sucks. Both MQA and DEQX are trying to get to better sound through, among other things, timing accuracy. It’s too bad both technologies can’t play nice together.