I'm not sure if I fully understand the question here, but I don't see any reason to go out of your way to get a 3.5 mm Sands cable. Those who think that cables make a difference think the stock cable makes the treble too much, and those of us who don't believe in cables think the TSMR-X sounds good with any cable. So I think your options are then whether you throw on any old 3.5 mm cable or if you get a DAC with a 4.4 mm output to use your current stock cable? I think it doesn't really make a difference; for what it's worth, I run my TSMR-X through 3.5mm, a cheap Artti cable and a JCally JM06 Pro dongle for portability and think it sounds great.
If you would like a 4.4 mm DAC, I recommend the JCally AP10 as a budget option. But I don't see much point in that for this situation alone, particularly given the negative reception the stock cable has received from some folk (it sounds fine to me but then again, so does any old $10 cable).
EDIT: Re-reading this, maybe you're asking if you should go out of your way to get a stock cable with 3.5mm in order to maximise the treble as you like the 100 setting? I would say no. You're better off getting an AP10 to use the cable you have which also gives you a bit of versatility and more driving power for other possible sets. I would still recommend against buying anything though and continuing to use any old 3.5 mm cables you have. Have you also tried the 011 setting which I believe is bassier than 010, but will smother treble less than 100? Also, you said you're using PowerAmp - that's the EQ software I use, why don't you make any tweaks you want with that?