I just read somewhere in internet forum says bi-wiring bypasses speaker's crossover circuitry. I am not sure that is true, well the fact is I am not expert in this area. But I would like to know whether it is true on M60v3. Currently my speakers are by-wired, and it sounds great.

The answer is no. When you bi-wire the M60 you are still using the crossover in the speaker.

The only time you would want to bypass the speakers crossover circuitry is when you are (active) bi-amping. The active portion being the use of an external crossover and separate amplifier channels powering each individual driver or section (bass, midrange, treble) of the loudspeaker.

Note that active bi-amping would involve physically removing the crossover from the circuit in the speakers and substituting an outboard, active crossover.

Thanks for the clarification.

GG, you almost reflected the reality of the situation in your post title. Bi-wiring is sometimes sarcastically referred to as "buy-wiring", because of the lack of any benefit for the added expense. All speakers with an internal crossover have a point where the wiring separates into two branches to go into the high and low frequency sections of the crossover. With one speaker wire this happens inside the enclosure just before the crossover network. With two speaker wires being used the separation point is moved back to the output terminal on the receiver. This makes no significant electrical difference and the procedure is audibly meaningless.

John beat me to the "buy wiring" term. As the others have mentioned or hinted, what you are doing really isn't achieving any sonic benefit. Years ago I tried it with my m80's and could not hear any difference, of course I was not doing a true AB blind test. I like the cleaner look of one cable, and less chance of having something loose or hooked up incorrectly.