It seems to me that the µBTR would be a good match for that earphone, both in impedance and cost. If you have extra money for the BTR3, I'd upgrade my earphones, first.
At 103 dB/mW, I don't think hiss should be much of an issue. I have 112 dB/mW earphones that don't exhibit hiss with the µBTR, though my hearing may be less sensitive to it than yours. Also, I use an iPhone, so my experience is with AAC, which isn't too different in quality from aptX HD.
Thank you for this, however the problem is the kind of headphones I want, which are light weight clip-on on ear type and not in-ear, are few and far in between. The only popular one I keep seeing is the Koss KSC75 but it seems a bit too heavy, the ATH EQ500 is too perfect at 20 grams, and the audio quality is not horrendous at the spec. I should probably post a separate thread for clip-on headphone recommendations but I've looked through some of the existing ones and couldn't find anything much superior.
I have an Avantree Cara II bluetooth transmitter and i get an ever so slight hiss when using it with the ATH EQ500, mainly because I listen 90% to audiobooks and podcasts at low volumes.
I've decided to go for the FiiO BTR3 even though it is overkill for these headphones, got it delivered yesterday.
First surprising thing about this little gadget is the weight, it is super tiny but also substantially heavy, I'd wager with the metal clip it's easly 30 grams or more, about the weight of a 9v battery maybe slightly less (the site says 25g but they might be saying that without the clip). On a thin t-shirt it can definitely be felt when clipping onto a shoulder. The clip is made of really solid metal, and feels VERY premium. in fact, the whole build is absolutely top notch, feels like it's an expensive product and has a lot of tech packed into its tiny dense frame.
NFC; this feature is slightly different from how I expected it to work, basically you need to hold the power button to power on the device first, and then use NFC to tap your phone and connect. On another NFC bluetooth headset I had, NFC would also power on/power off the bluetooth device itself, but that's not the case here. Would have loved to seen the NFC being the same but its not a horrendous issue.
Audio quality; now my headphones are by no means super power hungry at 103 dB/mW and i'm no audio expert either, but I have not heard even the slightest bit of noise or disturbance when listening at low volumes, mainly podcasts and audio books. It is excellent, definitely indistinguishable from a 3.5mm analog connection to my pc. The convenience of wireless at the quality of wired is what this device aims to deliver and at least in my case, delivers perfectly. Definitely recommended!