Having noted quite how similar the RHA SA-850 are to the SA-500 in design, it's no surprise that they offer a comparable sound signature. The high point is the low-end.
The SA-850 produce powerful, deep and satisfying bass. And unlike many headphones with a low-end focus, it doesn't result in an entirely confused sound. It's sophisticated enough to catch you out in those moments where a track smacks you 'round the head with a real low-end thwack.
They are, predictably, not immune to boominess, however, and they benefit from a taming through equalisation - which most portable audio players are capable of. Taking a few decibels off the bottom rung of an EQ is beneficial. This also helps to bring the SA-850 back into balance, because treble is left bubbling away on the backburner here. It doesn't have enough presence, and results in a lack of clarity in vocals and higher-register instruments. The bass is well-defined, the treble not quite so much.
The result isn't a sound that's completely muddy, but it does lack the spark and zap that brings music to life. Instead, it's dark-sounding and closed-in.
If a bass-tastic headphone is what you're after, though, the RHA SA-850 are a lot cheaper than most of the "trendy" on-ear sets that litter the high street. Less than half the price of the Beats Solo HD while offering punchier bass, we can see what the RHA SA-850 are aiming for.
The comfort issue is hard to forget, though, especially when similarly-priced on-ear pairs like the Sennheiser HD 228 don't suffer from the same problems. It's enough to ensure the RHA SA-850 miss out on our recommended stamp, but if you have less sensitive ears and are out for powerful bass, they're worth seeking out for an audition.
The top-end RHA SA-850 on-ear headphones offer much the same benefits and problems as the mid-range SA-500. Bass is powerful, providing the thump the Beats range claims to provide without the outlay. However, treble definition is not great, they're awkward to fit and the pads aren't the most comfortable around.