@Wild, thank you for the kind words! As to the Quads and Alphas; I've considered the question as well.
I'll start with another point of reference - the Denon D7000's. The Quads are the ciem version of the D7000's (at least to me). The Quad's highs are detailed and articulate, the mids are not as scooped out as the Denons. The bass has a really similar quality to the D7000's - powerful, robust, and bleeds into the mids a bit, which causes them to seem just a little scooped out. The D7000's suffered a bit more from this. Note that while this sounds pretty negative - it is not. I loved the D7000's, and they have a cult following that has driven the used price way up. The Quads have a similar warm, bass emphasized sound signature. The bass is boosted on the quads - have no doubt about that. It is boosted on the D7000 also. Both are really enjoyable headphones.
Now the Alphas. I've been listening to planers almost exclusively for the last year and half or more. There is something that the planers have, that balanced armatures do not. Some little bit of life and reality or something. I didn't notice it missing so much when I was listening with dynamic headphones. Pretty vague, hard for me to describe. I'll leave it at that.
The Alphas are near neutral with a nod to the warm. They are Dan's interpretation of neutral / reference / summit fi / accurate to live sound. I love them, Dan hits my preferred sound sig right in the small circle on the bull's eye. Not exact though. I love the Oppo PM-1's. I think Dan, not so much.
Anyway - the Alphas are not (or not nearly as much) bass boosted. They have deep, powerful, fast bass when called for. The mids are present and luscious. The highs vary depending on the doggie treat tuning. Mine started out a bit edgy in places, and with one dot and one disk each ear, are near perfect.
The Quads are less forward in the mids, and less present in the treble, but incrementally, not drastically. The bass is boosted over the Alphas, and has a bit more decay, and spans a broader frequency range due to the boost. Alphas are more accurate, quads are more fun.
If you love the Alphas and want to mimic the sound signature, I would consider what ever is the new 1964 ears version of the triple driver that came out with the original quads. Based on reviews I've read (
@project86's is a good one) of the triple, and my experience with the Quads (remember, mine are the old version, not the "i"), the triple, or whatever 1964 Ears' is tuning to that signature, will be a closer match. If you want a nice, bassier counterpoint, the quads are probably the choice.
My tastes have changed such that I kinda wish I had the triples now. I lean to less bass boosted, but still euphonic sound signature. That said, most of my listening to ciems is when I fly. The added bass stands above the airplane drone nicely.
Hope that helps. if you have more questions, I'm happy to keep this going. It's fun to see this thread pop back to life once in a while. I think I started it back in 2011 or so to chronicle my journey....