Very much appreciate how cordial this interaction has been :)

I will read through all of this! On your note about APO -- I don't use any onboard software EQ.

Finally, I have used my IEMs with the iFi Gryphon as well, which has a Burr-Brown chip and is supposed to be "warmer" than other devices but I found literally no difference between the Gryphon and the Apple Dongle in sound quality or frequency response. And even the Gryphon sounds less bassy than my TC44C unless I enable Gryphon's bass boost. Maybe it's just the interaction between my TC44C and my IEMs but that's what I've found in my daily use case.

Nonetheless, clearly, you have a ton of personal experience in the hobby, so I will absolutely respect your expertise and opinion on this matter. I just think my anecdotal experience is also worth sharing!

I appreciate all of your graphs! Lots to ponder and think on. I will note, it’s not just my head as I’ve had several friends and family A/B my units as well and they’ve also noticed a difference — without any priming. Also, again, the device you’re measuring is different from my own…there’s a possibility that the implementation of the 44C’s identical chipset is very different from the 44B.

Moreover, at a certain point, I think these graphs fail to capture audible differences between different amps. I am a scientist by trade, so I do appreciate the seeming objectivity that these graphs provide and I’m also wary that I’m susceptible to placebo effect. However, from my own experience with the hobby thus far, I think there’s no substitute for trying devices out yourself!

As an aside, do you happen to have measurements of the Cayin RU6 on hand? I’m curious if that measures any differently as it’s R2R and not delta sigma!

That’s all good to know! That said, I absolutely can hear a difference between the Apple Dongle and and the TC44C on my Nios as well in terms of bass response. 64 Audio Units are built to not be source picky, and I’ve found that’s generally true in most instances. For example, there is very little difference between the sound out of my Ferrum Erco and the Apple Dongle for my Nios. However there’s definitely an audible mid-bass boost at comparable volume levels between the TC44C and the Apple Dongle. Ditto when using my Burson Playmate 2 with OpAmp upgrades.

For detail retrieval, however, I do agree that I can’t hear any extra details between these sources, though some (like the Erco) provide better imaging capabilities than the others, which does make perceived detail better. Anyways, I’d encourage everyone reading to try out these sources and IEMs themselves before coming to conclusions…looks like you have the cousins of both of my devices, but I don’t think that’s a proper substitute for in-person A/B testing with the exact same ones.

Currently, I have the Apple Dongle, ddHiFi TC44C, and the Cayin RU6 on me as my daily drivers! I absolutely love the TC44C but it may not be everyone's cup of tea.

To me, audio is all about synergy. The TC44C is an extremely bassy unit compared to the Apple Dongle, with the latter being much more neutral. Thus, I don't think the TC44C is a great fit with my Symphonium Audio Meteor, which is itself a very bassy IEM. However, the TC44C sounds fantastic with my 64 Audio Nios with Fir Modules -- it adds in all of the bass that's lost when module swapping while still keeping the high-end details. Moreover, I also don't think it beats the RU6, as the RU6 has a larger sound stage and a more refined bass response.

All that said, where the Apple Dongle has both beat is in synergy with the iPhone. Going on walks with the TC44Cs or the RU6 is an absolute pain as audio constantly cuts out and the phone battery drains *fast*. In contrast, the Apple Dongle never skips a beat in addition to being extremely efficient, so it's perfect when I'm on the go. If I'm sitting down at a coffee shop, though, I will always choose to play music off of my laptop using the TC44C or the Cayin depending on which sound signature I'm in the mood for though (or if I just want to work, in which case the TC44C is far superior to the RU6 as the latter constantly clips).

tl;dr -- Frankly, I think these devices have completely different use cases. I agree that the TC44C DOES sound better than the Apple Dongle, but I think that comes down to one's preferred sound signature more than anything else.

A quick word of caution: I think the Oracles and Clairvoyance *do* require a decent amount of power to sound their best. So if you're going to allocate all of your budget towards just the IEMs themselves, I'd pick something more efficient.

I just got the 7HZ Timeless AE last week! While it is fairly power-hungry compared to most other relatively cheap IEMs I've tried, I've been able to run it right off of my phone using the Apple Dongle with no problem (volume around 70-80%). When I paired the Timeless with a variety of delta-sigma sources, the Apple Dongle, my M1 MacBook Air, DD HiFi TC44C, and Ferrum Erco, I really didn't find that much of a difference in bass response.

At the end of the day, you should do what you enjoy most. If you want the BlueTooth capabilities of the BTR7, go for it! But if you're just going to use it as a phone dongle, you may want to reconsider.