My decision on Thursday of last week is final about returning the iO-12 and keeping the excellent Solitaire T (ST). My plan is sending back the iO-12 on Monday of this week.
BUT last weekend (and in last few days) I'm using the 12 almost exclusively and only doing very few comparisons, meaning that I spending more time like I usually doing in my home and not thinking about comparisons or posting impressions in headfi.
So, this next comments are only about my VERY personal use of earphones and headphones.
Right now I'm not 100% sure I must returning the iO-12 (12) and selling my excellent Solitare T (ST). Why, after all my previous posts in this thread?
The number one reason is this: The volume control of the 12. With the 12 I have 32 volume steps, not 30 like I saying before (Sorry Fabik, you are correct is 32!) and I can changing the volume very quickly and having the exact volume I want -- I can't doing this with the ST, unfortunately. Volume control for me is EXTREMELY important, like I saying already, because I'm changing volume ALL the time. So, in last 5 days I'm having a great experience with volume control with the 12 that I don't have with my ST. This, I must insisting, is very personal and VERY important for me. Volume control in the 12 is very better than in the ST, and better, too, than in 5909, Bathys (this one is terrible!!), h95, px8 and many others BT/ANC headphones. I remember saying in the ST thread that I'm happy paying extra 100 euros for good volume control.
The second reason, not so important, but definitely is good having, is that the 12 having more maximum loud volume than the ST. With the ST this isn't a problem for me 97% of the time, but occasionally, when playing some old original masters (mastered with more low volume than today's masters but often having, by contrast, great dynamic range) I sometimes wanting little more max volume. BUT, this isn't really a strong reason, but is a good secondary reason still.
I rarely use my ST passively (headphone off with a 3.5mm cable) and I'm almost always using in BT "High Quality" mode 98% of the time, so this is other reason for maybe keeping the 12. If this being different, like is with several ST users that using the ST more in fully passive mode than BT mode, or even fully passive and balanced mode (a feature only available in the ST from any others BT/ANC headphones), then I definitely DON'T selling my ST. In difference with the 12, the ST's BT "HQ" mode is sounding incredibly close with fully passive mode. The 12 isn't. This is because of the ST's unique tech.
So, my big dilemma now is that I still preferring the ST's sound than the 12's. BUT the 12's sound is still excellent (with DSP on, not fully passive unfortunately) and very neutral /reference too. Like I saying before, the 12 is the second best BT/ANC headphone in sound quality I hearing in my life (only after the ST), and better, in my opinion, than the 5909, Bathys and very obviously than the h95 and px8).
If I keeping the 12, I will be missing the ST's excellent low-end extension. Is curious that some people saying the ST don't having enough bass!... then the 12 will having a little less for those people, even. The 12 is definitely NOT a basshead/bass lovers headphone because is very neutral sounding.
--ANC in the ST is better
--Fully passive mode in the ST is better
--ANC performance is (little) better in the ST (in my tests at home)
--Transparency mode is better in the ST
--Construction quality is better in the ST
--ST is better for travelling
--Personally I think the ST having better design aesthetically
If I keeping the 12, I have strong feeling that I will buying the ST again...
Terrible dilemma I have.