I recently purchased the nicehck hk6 from a fellow headfi member for 110.00 because I've read alot about them and wanted to compare them with my recent Toneking purchases. I didn't want to rush my comparison, so I gave them over a week of ear time to get fully familiar with their tuning. I know several people already own the hk6, so hopefully this will of some help.
First off, the hk6 uses a combination of knowles amd chinese BA's and that is apparent all throughout their sound. I find the the hk6 to sound pretty good and balanced throughout the whole frequency range. The upper mid range gets me though, as I hear a slight grain or unrefinement at the end and beginning of notes. I was able to smooth the sound out by using comply foam tips though. By itself, I find the hk6 to be decently tuned, but they're rather unrefined in comparison to the Toneking T66s. The hk6 are very lightweight to hold in my hand but feel cheaper made. The T66s are larger in size and filled, so they're heavier and seem to be much more quality.
The T66s sound more natural and lifelike to my ears, from the kick drum the whole way to the hitting of the high hat cymbals. Just crystal clear details and with a natural decay. The hk6 sound more artificial in comparison and the drum instrument really showcases exactly what I mean. The cymbal hits have an almost tizzy, digital sound to them.
I enjoyed my time listening to the hk6 and thought they were pretty good overall after I had acclimated myself to their sound. It was stunning though how quickly that changed once I put the T66s back in my ears after a week of using the hk6 exclusively.
I paid around 300.00 for my T66s and the hk6 retail in that range as well. I would be PISSED if I would've paid full retail for the hk6, but am happy with them for the 110.00 I paid. These 2 earphones aren't even in the same league and are several tiers apart. The tuning isn't drastically different, but it's the refinement and technical abilities of the T66s that sets them so far apart. As of now, the T66s are the very best I've ever had the pleasure to own, let alone listen to and they aren't even to my optimal sound preferences. I actually prefer a more neutral sound, rather than a musical and fun signature.
I hope I'm not misunderstood with what I'm trying to convey here. It's not that the hk6 are that bad, but rather that the T66s are that GOOD. I hope more people eventually give these new Toneking all BA earphones a chance and can find as much musical enjoyment as I have. At the end of the day, that's what its all about.