Setting your max clients to 220 on that setup is a terrible idea. You will probably cause the machine to start swapping as there is insufficient memory for each PHP process. It will grind to a slow halt. You should calculate your MaxClients based on the amount of load the machine can actually handle, not the amount you wish it could handle :-)
A conservative estimate of 20MB per PHP process would already put the requirements for 220 of them at over 4GB (twice what you have) and that's not allowing anything for the OS and anything else running on the machine. Its not an exact science figuring out the appropriate MaxClients, but you should find out how much the rest of the machine needs, look up the average Apache process size (ps), divide the available memory by that and then reduce it a little. Use this as you starting point for figuring out the MaxClients. Keep an eye on the available free memory for a while (vmstat) and gradually up that limit until you reach a comfortable working level for the setting.
Yeah - what's weird is that it didn't start swapping. I haven't really looked into it, but maybe because so many of the processes were downloading those MP3 files they didn't take up as much memory (although that sounds wrong as I'm pretty sure as far as Apache is concerned, a process is a process regardless of what's being downloaded).
At any rate it worked fine and was maxed at one point so hell knows why. I increased it gradually and was looking at the free memory etc. but it never exhausted it - but ps ax | grep httpd showed circa 200 processes.
I've put it back down to something safer now ;) when I have some spare time I'm going to try and figure out if/why it didn't appear to run out of memory when it looked like it should have.
But then again when I have some spare time I really just want to set up a better hosting environment that doesn't rely so much on apache.
A conservative estimate of 20MB per PHP process would already put the requirements for 220 of them at over 4GB (twice what you have) and that's not allowing anything for the OS and anything else running on the machine. Its not an exact science figuring out the appropriate MaxClients, but you should find out how much the rest of the machine needs, look up the average Apache process size (ps), divide the available memory by that and then reduce it a little. Use this as you starting point for figuring out the MaxClients. Keep an eye on the available free memory for a while (vmstat) and gradually up that limit until you reach a comfortable working level for the setting.