[r91085]

I got a bi-wire speaker. And I consider three options of amp. 

1. ST-10m x 2
2. ST-10 x 2 using bi-amp
3. Sta-6 x 4 bridged mode using bi-amp

It seem st-10m has better sound quality than st-10 . But I am curious if using st-10 x 2 for bi-amp has a chance to get better result than st-10m for bi-wire ?

The cheapest option is Sta-6 x 4. Sta-6 is obvious not at the same level as St-10 or st-10m. But it seems it can using it's own power for each output with less disturbance.  I am also curious how many gaps between this option and another two ...

Thanks for any suggestion or comment

[rustydoglim]

Definitely not STA-6. You have to consider the max power, not just power to each speaker.
Even though our design goal is for ST-10M to be better sounding (besides having more power) than ST-10, we do have a few customers still prefer ST-10.
If you speaker is 2-way, I am not sure bi-wire has the advantage. If it is 3-way, may be it make sense to do bi-wire.
My personal preference is to go with ST-10M.

[Mike6743]

It seems then that the best of the options from the OP would be ST-10M x2 with biwire cables.