There is no audio software without latency. The lowest that is feasible on Mac OS X is probably 4ms. Once you factor in distance and speed of sound, then you might see that 20ms of latency isn't really all that much.
Yeah, sorry that I said there was no latency, I do know that every software needs to process. What I meant to say was that the latency while recording was so low in fx Pro Tools, that I don't hear it. That is not the case with PD.
20ms * 343m/s = 7.546m
So if you are 7.5m away from one of your band mates, there will 20ms of latency just from the sound travelling thru the air.
This is of couse a correct calculation, but never the reality. I never stand more than maximum a couple of meters from my own amplifier, or else I will lose the timing if I hear my own sound with latency. And if you play at stages so large, that you are 7-8 meters from the drummer or other musicians, then you will almost always have their sound in your personal monitors, just a few meters from you. I actually had a problem some few times, when I tried to play together with the band, while making sound from the mixingdesk 10 meters from the stage. That is not recommendable (though you can do it with headphones).
So my point is here, that a realtime latency (including processing, ad/da conversion and traveling time thru air) above ca. 15-20ms is a real problem for the timing while playing together with a band. It can seems like in some of the comments on this list, that is neglected that the ultralow latency is making a difference and that you are on the wrong track if you wan't to use PD for that purpose. But I see very big potential and fun in doing this. I have skipped must of my analog effects, and instead use some real messy and funny delayeffects in pd.
I would still find it very interesting if anybody on list knows if it you can lower pd latency with better hardware to the unhearable or if 11ms (in the pd settings) is the lower barrier?