I've now listened to the GQ-30783 + RAB-32257 for about a week and have to say, it sounds really REALLY nice.
I had initially convinced myself that a DIY 3-driver IEM would probably have the sound quality of a pair of $20 - $30 ear buds but without the bass filling out the sound. After experimenting with a 6-driver config for the better part of 2 months, my pride/ego convinced me that a DIY 3-driver would be good enough for my teenagers, but not for me.
I will humbly report that I couldn't have be more wrong. Holy cow -- was I wrong!
During the research and development, I was worried about a lack of bass I was hearing with just using the GQ, which is why I paired it with the RAB-32257. I've been living with UE Metro.fi 200 (pre Logitech merger) for many years so not hearing that deep dark bass in the IEMs gave me pause. I thought RAB-32257 had the strongest sub-bass response when compared with the other RAB configurations, but now that I've double-checked, it looks like the RAB-32033 would have been a better choice if bass was my concern. Anyway, at $12/driver for the RAB, it made economic sense to pair this with the $37/driver GQ. The result? The bass -- it's totally there, and right at a level that gives some nice warmth to the music but not overly so. This is probably the result of some excellent isolation I'm getting from properly fitting shells and of course, correctly sealing the acoustic tubing at the nozzle. Funny story about the isolation of IEMs: As I was writing this, wearing my IEMs, I got a tap on my shoulder from my youngest. I was startled and pulled out one to say "Hi". He smiled in amazement and said "Could you hear me at all?" I smiled back and told him I couldn't hear anything except the music. He said he'd been standing behind me for a minute or two calling for me louder and louder each time. My FiiO X1 volume is currently at 35 and apparently I'm oblivious to the world around me at this level.
The details I'm now hearing are pretty magical as well. The best way I can describe it is like this: A long long time ago, when I got my first home theater surround sound system setup, I put in a DVD I was pretty familiar with "Saving Private Ryan". While the sound was now amazing, there were parts of the movie where machine gun fire was occurring. Without surround sound, you could hear the tinkling of the shells as they hit the ground, but with the surround sound playing, you could actually count the shells as they hit the ground. Listening to these IEMs reminds me of that day. I feel like I know how many beans or bb's are in the percussion shakers and they rattle in the background of some songs. I can hear the zipper-like sound of calloused fingers moving down the strings of the fret board in various acoustic songs that I couldn't hear before. If there's one complaint, it's that when a low quality mp3 now queues up, it sounds muddy and makes me question if it's the mp3 or the IEMs. I'll have to do a search on my mp3 library and replace those lower bit rate recordings.
Overall, the sound of this config is pretty damn fine to my ears.
For anyone who already has a GQ on-hand and looking to do some experimenting by adding the RAB, the configuration I'm using is:
GQ-30783 - 2.0mm x 19.5mm tubing with a Knowles Green filter (1500ohm) + additional acoustic material to refine the 2kHz - 3kHz frequency response and further mellow out semblance if you hear any.
RAB-32257 - 2.0mm x 15.5mm tubing with lightweight acoustic material to refine the 2kHz - 3kHz FR.
The good news, is that for those who like more treble, the nondescript extra acoustic material can be omitted. And, this config requires no crossover, other than the one that's already build into the GQ, of course.
CheersRAB-32257
