Headphone wise, the Sony WH-H900N, WH-1000XM2, WH-1000XM3 support aptX HD. I’m sure there are others. But they also support LDAC which is better still. Player wise, I know Sony’s NW-WM1A and NW-WM1Z, and I believe the ZX300 all support aptX, aptX HD and LDAC (as well as AAC and SBC).
aptX HD differs from aptX in terms of available bandwidth … a bit over 500 kbps, which means it can encode a 24/48 bit stream using, in ideal conditions, about a 4:1 compression ratio. In all cases this means it’s a lossy-protocol (i.e. has to rely on perceptual encoding techniques rather than being bit-perfect - though that’s not to say it isn’t audibly transparent in good conditions), and like all Bluetooth audio CODECs has to support constantly changing available bit-rates.
LDAC has about double the bandwidth of aptx HD (again in ideal conditions), and in “Quality Priority” mode (selectable) has enough bandwidth to use a more FLAC-like encoding for 16/44.1 and 24/48 content (about a 2:1 compression ratio). Full bandwidth isn’t guaranteed, however, and if you get dropouts there, and switch to “Connection Priority” it’ll use similar perceptual encoding, albeit with lower compression ratios, to other Bluetooth CODECs.
Beyond current signalling conditions, the CODEC is really what sets the quality limit for Bluetooth Audio.
Everything supports “SBC” - but that’s the least desirable mode and often has highly audible artifacts, even in good conditions. For example, my Hugo 2 only supports SBC and aptX … so coming off an iPhone (uses AAC instead of aptX) it is stuck in SBC mode - and it’s unfortunately VERY easy to tell.
AAC and aptX are the next tier up. They are very similar in terms of achievable bandwidth, both being better than SBC. While more and more gear supports both, for a good while you were stuck choosing between them (e.g. Sennheiser initially favored AAC, so Android users got stuck with SBC).
Then you have aptX HD, support for which is growing, but slowly. It was annoying to discover that a recently released, almost $3,000, mobile DAC that has Bluetooth support just stopped at aptX.
And finally at the top of the pile is LDAC … which is mostly supported by Sony products at the moment.