I have a pair of Acoustic 1x15 cabs I run with a 500 watt Hartke head. I like the rig, and the pair of 1x15s over, say, a 4x10. But it seems a little muddy at times. I can't afford a major upgrade, but I found some new Celestion neo speakers for $125 each. Is the upgrade worth it? Or should I save up for a 4x12 or better quality 1x15s? Any opinions?