The 115 will not add much to your 410. You are better off without it, unless the 410 alone is not loud enough-in that case your best options would be a more powerful head through your 410, or (much better/louder) either a single, larger 4 Ohm cab (810 or 610) or adding a 2nd identical 410.
The 410/115 will work, but isn't optimal. The 410 will be far louder than the 115 and it's doubtful that the 15 is tuned lower than the 410 anyway. It WILL be a little louder than the 410 alone (but not much). The fact that the 115 will raise the 410 off the ground and get it closer to ear level will probably do more to change the perceived volume and clarity (on stage) than whatever comes out of the 115.
In theory, you 'll run the risk of blowing the 15 if you are cranking or pumping up bass in with your eq, since the 15 will reach its' limit before the 410 and you may not hear the cab distorting until it's too late....this is probably not an issue with a 350 watt head unless you are diming it, but you never know. Search topics like mixing drivers on this site, pour yourself a dwink and read up :-)
Some of my heroes: Jean Beliveau, Richard Dawkins, Galileo, Hubert Reeves.....
Last edited by lomo : 10-18-2013 at 02:34 PM.