Steels help but aren't a requisite for 'piano tone' - Circle Ks are a hybrid steel/nickel and can get you where you're headed. They won't be as bright as steels out of the package but the tone you get from them will last longer than the zinginess you find in new steels. Tone will shift with any string, mine included. I believe the shift is slower and less radical with my stuff.
On EXLs tone shifts a lot with ageing IMHO. And I'm not anal abut that HF ziiiing, I don't crave for it, and I don't mind it as long as it's not overpowering rest of the spectrum. Basically, something like
this, with clear and present 2nd 3rd 4th and 5th harmonic, even spectrum and long harmonic decay - but I wouldn't mind at all more open and present mids/highmids.
Balanced tension goes a fair ways in evening out volume disparages from string to string - you ought to see some improvement there.
Yes I certanly hope so (in EXL165 set, D has >20% more tension than E, and it is noticable). I was ready to buy EXL singles to form more balanced set untill I'v found out bout Circle K.
You will get plenty of attack using a pick.
Do you feel the .105 you have is too floppy, or is it too floppy as compared to the rest of the set? The answer to this question will let me know what to suggest to you.
That is quite a complex issue. First about attack, I feel that EXL has strong but flabby attack, like when you compare badly tuned bass drum with properly tuned one, you get loud FLAB instead of tight BAM. Since most of people comment on how Circle K are "focused" I hope to mitigate a bit this issue.
About floppy-ness, well I really can't tell if 105/40lbs feels floppy by it self or compared to whole set, since whole set feels off. For some time I was set on about getting 50lbs set, "tighter is allways better" idea, but recently I figured out two things: A and D actually feel too tight, my left hand in particular seems to struggle a bit when fretting, and I strated to play with dropping tune on D and G and I noticed that both plays nice and easy even droppped to A and D. Dropping tune on E is a problem since E quickly loose tone, and 8th note runs become indistinct mush (maybe I should learn to avoid 8th note staccato lines on E string anyway).
What bugs me is that I've read lot of comments (your website included) that Circle K feels more flexible than other similiar tension strings. While it sound logical that also means more even and richer harmonic contet, do they actually feel flabby-er (I allways strive for lowest action possible, will this "higher flexibility" set me off?).
To cut a long story short, I figured out that .106 E based balanced set would be safest bet (106 80 58 43, right?) but, judging from what I wrote feel free to recomend me some other option (I would really like to try 3 different tension balanced sets but that would be quite a leap of faith and budget).
Finaly, one weird question: have you tried, or you know someone has tried, "inverted tension" set, something like 106 76 55 40 ?
thanks
Urosh
edit: one more thing, do Circle K have more friction (under fingers) than average nickel like EXL?