pedro nicoli said:
but it work flawless on my desktop PC...why it wont on the macbook?
That is impossible to answer.
Every Analog to Digital and Digital to Analog conversion has latency.
The only way you don't, is if you take an analog monitor output from *before* the conversion -- which, naturally, cannot include any of the software effects.... but will include whatever effects your Boss is creating in the analog realm.
So the answer about your desktop PC is: You have latency, but in your case (described as "flawless") that latency is within your own personal tolerances and you find it OK. The same goes for the Mac. There will be latency, but Macs generally are quite good compared to PCs in this regard, so you can expect that the latency on a MacBook Pro or whatever to be comparable to the PC.
The amount of latency, on either Mac or PC, depends on the speed of the machine's CPU, the efficiency of the interface and its software drivers, the type of software you are running and the number of plug in effects (more load = longer latency), any other slowdowns in the system (drive performance, RAM performance, OS performance), and is ditectly controlled by what you have chosen to set the buffer size to.
Smaller buffers mean lower latency. But smaller buffers also mean glitching or dropouts if the amount of data incoming exceeds the ability of the machine to keep up. Larger buffers mean that you can record more simultaneous tracks, and have more plug-ins and operations running at the same time -- at the expense of longer latency. It's a trade-off.
Also remember, latency is only an issue when you are recording live instruments and monitoring through the software. Latency is not an issue if your are monitoring pre-conversion (as above) and Latency is not an issue for playing back tracks and software generated instruments because almost all sequencers/digital audio software has latency compensation where the tracks are automatically slid in time so that they line up well on output.
