DX100 and HM-901 sound great, but the problem is they are so big and bulky that they are not suitable for pocket use unless you wear a jacket during summer. If you try to put them in the pocket of your jeans/trousers/cargo pants, they're just too big and bulky (I actually owned a DX100 and found this out, personally). So what's the point in having a DAP that's so bulky, you have to carry it in a rucksack, during the summer months? You may just as well go for a 2-box stack (DAP+Amp or DAP+DacAmp).
So I feel it is extremely important for Fiio to be very, very clear about their intended target market for the X7. Is it going to be a bulky single-box DAP like the DX100 or HM-901, which is capable of driving cans but is not much smaller than a 2-box stack, or is it going to be aimed at IEM/CIEM users who wish to use a single-box DAP in their pocket even during the hot seasons of the year?
I am interested in TOTL SQ, but I do not feel that the X7 needs to be able to drive power-hungry cans like the DX100 and HM-901 are able to.
I understand that higher operating voltage still requires a bigger battery, and that it is a very difficult thing to balance the demands of SQ vs size/weight. But I feel the DX100 and HM-901 went too far and became too bulky. I like the DX100 and I like it's SQ, but it's just too damn big to walk around with in one's jeans pocket. I do not wish to buy a DAP that exceeds 20mm thickness and 230grams weight.
I was initially very vocal in my disappointment that the X5 power output was being reduced from it's originally-intended spec, but it actually turned out to be a respectable power output and I see no reason for the X7 to exceed the power output of the X5.
The Calyx-M would be an excellent starting-point for inspiration for an Android-based TOTL pocket DAP. It is obviously a very complex circuit design, but the DAP strikes a good balance between size/bulk and probable SQ, with a careful implementation of the DAC. 90mw isn't very powerful, but it may be just sufficient for CIEM-users (I am reserving judgment until I have heard it). The Calyx-M is 15mm thick and 230g. I could live with a 5mm thicker equivalent DAP from Fiio, but would prefer, if possible, a slightly smaller length (i.e. based around a slightly smaller touchscreen), and slightly less weight.
I see no point in Fiio producing an amazing-sounding DAP if it ends up being almost as bulky as HM-901 / DX100. That would just be a waste of time.
Edited by Mython - 4/12/14 at 1:41pm