USB DAC/amp (dongles)

Works fine with iPad and iPhone with Cayin lightening to USB C Cable

 

Good dongle resource. He's got the RU6 ranked #2 out of 70 reviewed.

https://andyaudiovault.com/donglemadness/

 

It's worth noting his number 1 choice is the CEntrance DACport HD which is apparently class A and really designed to be connected to laptops/computers and burns through phone batteries like they're tissue paper. So the RU6 is really the top rated dongle that is designed to work with phones.

 

Apparently Apple is a limiting factor. In this post, the Cayin PR guy says that the engineers wanted a more powerful amp, but that wouldn't fly with Apple products and he talked the engineering team out of it. As a non(anti)-Apple guy and mostly laptop listener, it's a shame.

https://www.head-fi.org/threads/cay...c-with-head-amp.960113/page-105#post-16760107

 

As an Apple user, I appreciate that Cayin made their device compatible with mine, as IMO dongles are more about convenience. If I want more power I have the ZX300.

Also I understand why Apple has the restrictions they do. It helps strike that balance between functionality and battery life. Would it be nice for Apple to have a setting that bypasses the restriction? Yeah, absolutely. And maybe at some point that will come. But for the majority of users, maintaining battery life through a day is going to be a higher priority than maximum power output, so I get why Apple made the decision they did.

 

Not to derail, but does Apple have better battery life than Android? That's not my experience. If not, then why does Apple output less power?

I get their decision - it's a smart one. It would be cool if they offered two versions, or if the SE was for Apple and balanced for higher power. No idea if that would even be possible.

 

Most phone manufacturers basically just aim for a day of moderate use for phone battery life, and don't try to go past that because bigger batteries increase the weight, size, and cost of the phone. So chances are that Android and Apple phones have similar battery life because Apple, Samsung, Sony, Google, LG, Motorola, etc. are all aiming for about a day of battery life with moderate use. It is possible that Apple is getting better battery life in that their batteries might be lower capacity than the flagship Android phones yet still get comparable performance (this is unverified on my part, just a guess). I know the smaller iPhones, the SE and the Mini, do have battery life that some people would consider to be unacceptable for a phone in 2022 because Apple is being limited in capacity by the smaller phone form factor. Whereas the Pro Max models have battery life in excess of what most people need because the phone is so big that they can fit a massive capacity battery in there without making the phone thicker.

In terms of battery management, Apple is more hands on than Android manufacturers. Apple far more actively manages the battery in an attempt to deliver that full day of moderate usage that consumers expect. Apple also limits certain battery intensive features. For example, Apple didn't introduce a 120hz screen for the iPhone 13 Pro models, they introduced a variable rate screen that maxes at 120hz but goes as low as 10-15hz IIRC based on what content is on the screen. This was a deliberate choice to ensure that their phones don't run continuously at 120hz as many Android phones can and run through the battery while the user is reading an ebook or web article. Their standard 5G setting is to use less data and ramp up to full 5G speeds only if the application calls for it. In general, Android manufacturers do not manage their features nearly as aggressively as Apple does. Most Android phones with 4K 120hz displays will let you run those displays at max settings as long as you like, even if it cuts the battery time in half. Similarly, Apple limits the power output from the phone and most Android phones don't. This is an active choice on Apple's part to balance functionality with battery management. And while I wish there was a setting to let me bypass this, I completely understand why Apple made the choice to put the limit in and also why there isn't a bypass setting.

Edit: Apparently according to Andy some Android 12 devices are now instituting similar current draw limits as well, so the honeymoon might be over for power hungry dongle users.

In regards to the RU6, I have definitely noticed that the higher quality of the source, the better the playback. When I plug the RU6 into my MacBook Pro, I am genuinely impressed at the level of sound reproduction I get. Lately I've been listening to the RU6 from the laptop with the Timeless and choosing that over my desktop level system. I don't get that same level of performance out of my iPhone. However, that doesn't mean that Android phones would necessarily sound significantly better. Quoting Andy from that HF RU6 thread:

It sounds like the issue that iPhones present to dongle makers is limiting the max power output, to the point where the most powerful dongles are wholly incompatible with iPhones. I am very glad Cayin didn't take that route, because the RU6 still sounds good out of my phone, even if not as good as it does out of my laptop, and it can power a surprising range of headphones decently if not perfectly. But again, to me a dongle is about convenience more than the best possible portable sound, and IMO should primarily be used with IEMs. I sincerely hope that Cayin takes the momentum of the RU6 and uses it to make a mid-tier R2R DAP or portable DAC/amp that runs off its own battery and can bypass the iOS draw limits, because I think such a device would punch well above its weight in terms of performance given how good the RU6 can sound with the right source. But I think that going up a device size would be the right solution there, not shutting out iPhone users to make a dongle a bit more powerful but still nowhere near the level of a good desktop amp.

Yes, this was confirmed to be as designed in the HF thread.

 

Yes, I feel it’s part of their design and implementation.
We will get these glitches after every 10steps, I guess

 

I used to have the original Dacport. My laptop battery life was definitely a lot less with it plugged in
It also made a nice hand warmer in the winter. Non-hand use at your own risk.

 

I should point out I don't agree with his assessment of the tone of the RU6, I definitely perceive it was warm tilted, whereas he calls it neutral and reference. Could just be a difference in the way we define/apply those terms. I also hear a mid-bass emphasis and some rolled highs whereas he found the FR to be balanced and not over/underemphasized in any one area.

 

I feel all that's required now for the next r2r dac/amp or dongle for that matter is to have an internal battery for clean power. I also realized that I hardly want to go through the trouble of dongling and wires on the move, so its more intended still for more transportable listening in a hotel room, traveling desk environment. Even a 40 minute subway ride in nyc doesn't justify dongling imo(done it multiple times, and wasn't worth the fuss for audio quality that is already botched by the subway noise). I agree its sort of dap or full wireless(Hoping the airpods 2 pro actually can take advantage of lossless).

 

So the reviewer calls it a "rail to rail resistors array", but just want to clarify for anyone reading that review that the topology is commonly referred to as R-2R or R/2R because each leg/rung of the ladder is populated by one resistor of X value followed by another resistor of twice the value, for each digital bit being converted to a voltage. Just clarifying cause this is first time I've ever read the topology referred to as "rail to rail" which sounds like either some kind of shipping service, or a car bouncing between guardrails on a highway like a hot dog in a hallway.

 

That's because it's wrong. I'm guessing that he did a quick web search for the meaning of "R2R" and happened to come across "rail to rail" before he found any descriptions of a ladder DAC.

In an electronics context, the rails in "rail to rail" refer to the lowest and highest voltages in the circuit (I assume the etymology is either from bus bars or oscilloscope traces), so "rail to rail" is an adjective that basically means "full range".

 

Initially (pre - 50 hours burn in) I thought it was warm leaning (with slightly etched treble), but further burn in made it neutral. The mids got pushed out, the treble is not super refined or rolled off (but is good enough), and the bass took a step back. It still has that slightly fuzzy and non ringing sound signature which can make it more pleasant to listen over longer term - but it's neutral for me now.

I listened to the Hiby RS6 R2R and its focus is certainly more on the mids and bass density than the RU6 - I perceive it as more weighty (in addition to also sounding more open and less etched)

With these R2R sources, it seems a lot of burn in is needed (in the hundreds of hours) before the sound signature settles which is probably why I've read so many mixed tonality impressions.

I still it's a great dongle in comparison to others, it's very musical.

 

As a recent birthday present to myself, I've got one of these incoming. After I've had my time with it, I'll work with @rhythmdevils to put an RU6 out on personal loaner.

 

I'd be happy to send out my Lotoo Paw S1 on a personal loaner tour as well, if there's interest. It's been superseded by the S2 but it pairs pretty well with the sensitive CFA Andro and Solaris.

 

Has anyone tried the Xduoo Link v2? It has the same Cirrus Logic DAC chip that is in the iFi Go Blu which a lot of SBAFers liked. From older reviews it appears that this dongle may have originally had a Sabre chip.

 

I'm still enjoying the heck of out of the RU6. I was initially disappointed that the RU6 didn't have a lineout feature. However I've tried it at 100 volume going into my Vali 2 and it sounds lovely! The Vali 2 adds a little stage size and dynamic umph.

On the go, I've recently switched to SE after going for the increased power of balanced. It sounds a little smoother or purer to me than balanced, which isn't true balanced.

 

OE audio makes nice OTG cables that are actually up to USB cable standards. I doubt any of the others on the market are. OFC copper and shielded and the right impedance, etc.

https://oeaudio.shop/products/oeotg-digital-cable

I wish I saw this before buying the Lutooo OTG cable. They're the same price.