What do you use for a transport? Could you do better without spending a fortune? I bring this up because I'm continually surprised at how little attention some people give to this aspect. I've met quite a few enthusiasts who go all-out on exceptional amplification, quality D/A conversion, precise speaker placement and/or top-class headphones (often with custom cables), signal reclockers, linear power supplies, and so on. And yet when I ask about their transport, the answer seems out of place; it's often just a standard PC or MacBook, or occasionally a decent CD player. I suppose they figure the DAC does all the heavy lifting, so why bother?
In my experience, that is unfortunately not the case. Transport quality does in fact play a potentially significant role in overall system performance. Certain DACs can be more picky than others, but in most cases a quality transport is worth shooting for - especially when everything else in the chain is up to a certain level.
That said, I have also seen people go waaaaaay too far in the pursuit of a quality signal. If you spend more money on your transport than your headphones or your DAC... you're probably doing it wrong.
This leads me to one option for doing it right: the new iDAP-6 from Cayin.
I already started a thread about this device a few months ago, so I won't repeat the same material here. This is more for documenting my experiences with the device after fairly heavy use. Please read through that initial post for information, then come back here to finish it up. I've identified a few weaknesses and a whole lot of benefits - so let's get right to it. I apologize in advance for the somewhat scattershot approach here... this is sort of a stream of consciousness review, or at least much more so than my usual write ups. Hopefully you can still follow along.
Cutting to the chase, I'll say the iDAP-6 is killer for localized playback. By that I mean attached hard drives, USB sticks, and SD cards. I use it as a bedside rig with matching Cayin DAC and amp, and don't need any sort of networking whatsoever. Just plug in a card or drive, and go. The interface is logical, the controls simple, and the results sonically impeccable. It's a big improvement over the laptop I used to have in this system, both in terms of sound quality and user experience.
If you've only ever used a standard PC or Mac as transport, you might be surprised at how much performance you've been missing out on. This will vary from DAC to DAC, but in most cases a quality DAC will benefit from a better transport - sometimes by a little, sometimes by a very large amount. Assuming you've got decent amplification and a nice set of headphones/speakers, you'll most likely hear superior articulation, more abundant microdetail, more explosive dynamics, and a greater sense of ease in the treble region. In some cases it really can feel like a DAC upgrade.
(pardon the blur, the text was scrolling and I used a slow shutter speed)
Some DACs have their own processing which helps minimize the importance of transport quality. If that's the case with your device, you might not notice much difference... though some models have options to reduce or eliminate that processing. This applies to the Wyred 4 Sound DACs which have multiple settings for jitter reduction. While using the iDAP-6, I found the lowest possible setting to sound the most pure. Same with the Yulong DA9, which has a simple "on/off" selection instead of a sliding scale like the Wyred devices. In contrast, when using my MacBook as transport, I prefer the DA9 switched to "on" for jitter elimination, and with the Wyred DACs I prefer it turned up almost all the way. If I eliminate jitter reduction and try using the MacBook, the result is rather unwelcome... fuzzy dynamics and harsh, metallic treble.
I've got a few gatekeepers for transport quality these days. First off, I compare the MacBook over USB, which represents a relatively standard consumer-oriented setup. The dedicated transport being tested should be able to ace this comparison, or else I won't proceed further. Next up is an Oppo BDP-105 via coaxial output, which is a step up if not a drastic one. I hear very minor improvements when making that switch. It's not an obvious thing right off the bat, but I do find long-term listening becomes less fatiguing. If a transport can do better than the Oppo, I consider it worthwhile. Lastly, I break out my Simaudio Orbiter, which was a really high-end ($7,200) universal player released about a decade ago. It sports AES/EBU, BNC, coaxial, and optical outputs, all of which are equally superb. The Orbiter is excellent, and I hear a pretty noticeable improvement when I put it in place. Little details like soundstage height start coming in to focus, while dynamic swing is much larger and treble significantly cleaner. If a transport comes anywhere near this thing, it's a definite winner.
The Cayin iDAP-6 matches my Simaudio spinner in performance. This is an impressive feat. For reference, I've compared the Orbiter to more expensive players from Esoteric, EMM Labs, and Accuphase (among others). While those tended to sound better via their analog outputs, the Simaudio was the best of the bunch on transport duty. By extension, that means the little $799 Cayin iDAP-6 keeps up with those megabuck monsters when feeding a separate DAC. Surprising? Not really... by dedicating the device to transport duties, and leveraging the strengths of file-based playback, the iDAP-6 ends up being more focused than those behemoth players. Factor in Cayin's general lean towards high-value, and the build quality being high but not absurd, and it starts to make sense.
There are some options of the iDAP-6 which I just don't use. For example, Bluetooth streaming. It's aptX equipped (for outgoing streams) and can stream to or from other devices. That's just not something I'll ever use on a device like this. I do use Bluetooth to interface with a remote app on my phone though (more on that shortly). iDAP-6 plays Airplay for Apple devices, which I won't ever bother with. There's also WiFi and an Ethernet connection which allows streaming - but it's not perfect at this point. While it does play music off my NAS, there's an issue where it requires me to log in every session.... it won't save my login information like most other devices will. Until Cayin fixes that, it's not something I care to use. But again, I think the strength here is local file playback, so I probably wouldn't use the NAS much anyway.
Controls are very intuitive using the spinning, pressable knob plus a back button. Anyone can figure this out in minutes. However, using the HiByLink app on my phone is really nice too. It offers a clean interface with expanded options like search which wouldn't be tenable using just the front panel knob. I almost think it's a requirement when dealing with massive libraries. If I just plug in a 256GB USB stick filled with reference tracks, I'll usually stick with the knob.
One complaint, albeit minor: I did run into a few situations where the SD card or USB stick I was using ended up being too slow for playing hi-res PCM or DSD material. It worked, but would occasionally have tiny dropouts within the first few seconds of playback. I speculate this to be when the player tries reading ahead for buffering, as well as loading the image file for album art. Slower cards or USB drives just don't have the speed, so the audio drops out momentarily, and then works flawlessly for the remainder of the track. Still, this is definitely something I couldn't live with, so I make sure to use fast Samsung storage which avoids the issue altogether. Portable SSD storage is great, and even spinning platter portable hard drives are fine - or at least the few I've tried did the job without issue.
Without question, my favorite output is the I2S over HDMI option. Obviously you'll need a compatible DAC - I used a PS Audio Stellar Gain Cell DAC as well as a Wyred 4 Sound 10th Anniversary DAC, and both sounded their best via I2S. Based on past experience, the PS Audio DirectStream and NuWave DSD will offer similar benefits. I2S isn't always the best input on every DAC, and can get frustrating due to lack of standardization. But I'd say Cayin made a good choice sticking with the PS Audio/Wyred 4 Sound format.
Other outputs sound great as well. My second choice is usually the AES/EBU which tends to sound the best on a lot of DACs. BNC and coaxial are both present, as is optical, all of which sound quite good too. And don't forget USB - the iDAP-6 can also work with most DACs via USB, as long as the DAC is comfortable with Linux. Honestly the difference between all of these is fairly small, so pick whichever one your particular DAC likes the most. Worth noting: the USB, AES, coaxial, and BNC outputs can handle up to 24/384 PCM and DSD128 (DoP), while Toslink is limited to 24/192. I2S goes all the way to DSD256.
To wrap this up, let's talk about the full Cayin stack. My bedside rig consists of the iDAP-6, the matching iDAC-6 tube DAC and iHA-6 solid state amp, plus the HA-1A MK2 tube amplifier. This makes for a stunning combination, both visually and sonically. The iDAC doesn't have I2S (Cayin intends to do another DAC one of these days which does have I2S) so I just go with USB for simplicity. I go balanced out from the DAC to the solid state amp, and single-ended out to the tube amp. Headphones getting the most use lately are the HD650, the Focal Elex, and the Sony Z1R.
This system approaches end-game levels. Running an HD650 from the HA-1A MK2 (with full compliment of Amperex Bugle Boy tubes) makes for a supremely musical, somewhat lush presentation, with unbelievably flowing vocals. I switch to solid-state amplification for the Focal Elex, which has resolution for days using a Moon Audio Silver Dragon balanced cable. This makes for a supremely "open" presentation, with stunning imaging and soundstage accuracy. I'm still trying to come to grips with the Sony.... it's nowhere near as technically accurate as the other two models, but nonetheless offers its own unique take on the music. Which I sometimes prefer. It reminds me of speakers from Zu Audio or Audio Note - measurements are not great at all, but somehow the sound can be really inviting with the right music. Interestingly, I like the Sony out of both amps, depending on my mood. I can't decide which is actually the better match. Prior to this trio I spent a lot of time with the HD800S, Ether C, HE1000, THX00, and a modified/fully balanced AKG K812, all of which sounded top-notch with the Cayin gear. Aside from having too much gain for IEMs, there's not much this system can't do.
I really feel that the iDAP-6 is an integral part of getting this system performing at such a high level. It's obviously a perfect aesthetic match, but more importantly it just sounds flat out better than most other transports out there. I can't think of anything that touches it for the price. The closest competitor would probably be a streaming solution from SOtM or Sonore, plus a matching linear power supply. Those will end up costing more than the iDAP-6 and won't sound any better. Plus it's just a different experience - I think of those as being primarily centered around Roon. Now, I'm a huge Roon fan, and I use the SOtM sMS-200 with great results, but the iDAP-6 is something else entirely. Local playback has its charms, offering a simplistic experience more akin to grabbing a CD and pressing play. If Cayin can eventually iron out the NAS connectivity issue, that would give it a broader appeal, but for my needs it's just about perfect as-is. If you're looking for a transport upgrade, with or without the matching Cayin DAC and amp: the iDAP-6 is an incredibly strong contender.