I guess a stupid question here... so why didn't Fiio utilize a better DAC that supports native DSD instead of a software conversion ?? So in the end the X5 is just a souped up X3 ??
I was really hoping that the X5 was the DAP version of the Idsd... would have been a great product.
Probably just price. The PCM1792A used in the X5 is priced at $7.08 /1ku to $7.21 /1ku. The equivalent DSD1792A is priced at $11.18 /1ku to $13.32 /1ku (all numbers taken from TI:s website). So it would mean a bump in price for the parts and the implementation would probably cost a bit more also. It wouldn't be AK territory but i can see why FiiO decided to go with the "lesser" chip, only sacrificing one feature that CAN be done with software (Probably not as good but still better than nothing.).
Though I'm no accountant and i have no clue about the actual cost of the implementation of both chips, i would still say that the DSD1792A would be a welcomed upgrade for a X5 mark II or maybe the X7.
Actually that will be the wrong guess, but you are right that money is a factor. When you buy chip in bulk from manufacturer (as FiiO does), you get special deal that is far cheaper than you buy from distributor as you are cutting out the middle man. You will be surprised how cheap those chips will be. So no, price isn't a factor.
The problem doesn't lie in the DAC, but the DSD format support among SoC (System-on-Chip, or "enhanced CPU chip" for those non-geek). Most SoC that you will find on DAP is RISC based (similar to those find on smartphone), and they have no native support for DSD, which is a relatively new compared to the industry standard PCM format (2005 vs. 1956). Therefore if you want direct DSD support, you need to "rewire" (= hack) the SoC in both hardware and software to make it supports DSD. But when you use PCM, everything has been implemented nicely.
Basically, when you play music on DAP (or in fact 99.95% of all PC soundcard), the SoC / CPU read the digital files (mp3, FLAC, etc), coverts it to the standardized PCM format, send via the I2S channel ( or IIS, Inter-IC Sound) to the DAC, which coverts it to analog sound. These are all pretty much how the computer's sound works since the early days. But I2S doesn't support DSD format at all, as DSD was invented much later in time. Therefore to do direct DSD decoding, you must bypass I2S and use a dedicated channel to send the signal to the DAC, and the DAC will require a dedicated DSD port to listen to this signal (which can be integrated into the same PCM listening port with some clever design, but that's another story). So to do this in a DAP, you need to specially rewrite the firmware code to tell the SoC to differentiate PCM and DSD, then implement a GPIO (general purpose I/O) channel to reroute DSD signal to the DAC - this might sound easy on paper, but the actual implementation, especially how to write a brand new firmware, is a major headache.
When you buy a SoC from a SoC maker, you don't just buy a chip - you are buying a whole "solution". This mean the SoC maker is your solution provider, including sufficient firmware support and bugfix. If you are Apple and you own a team of software engineer of your own, firmware is not a problem for you. But when you are a small company like FiiO, you need to either rely on the SoC maker to iron out the bug or you need to invest big money onto hiring a team of software engineer or even outsourcing the firmware to a software company - and believe me both of the later will cost a LOT of money. So to do DSD native decoding, you will have to invest a lot of money into a brand new firmware since the basic coding from the SoC maker isn't likely going to work, then you need to face a lot of new bugs since you are basically hacking a solution of your own together. To put it short - it is a lot of pain for very little gain, not un-do-able but not easy in anyway as well. On the other hand, software DSD-to-PCM convert is much easier and cheaper to do, and therefore it is the common choice for most. So now you know why the very few DAP with DSD native decoding cost so much - but if you really think about this - does DSD really is that superior to PCM that worth the much of an investment? Personally I have read argument from both sides (and some of them are heavy weight icon in the audio industry and scientific / engineering field) and so far there isn't a clear winner yet. It is, as far as my opinion goes, not the magic dust that automatically makes music sounds better, and therefore shouldn't warranty some much attention when there are better ways to improve SQ. If DSD really proves to be better in future when it is much more common, then perhaps we will see a lot of DSD decoing DAP on the cheap.
Kind of longish, but hope these makes sense.
Edited by ClieOS - 3/12/14 at 6:29am