Having been using the Ashdown MAG 250 410 for about 8 years now - I have one of the original UK built ones rather than the new Chinese manufactured - I've always been dissatisfied with the thump this produces at higher volumes (50% or more). A while ago I added an extension cab for a couple of gigs. This small cab had a Delta15A installed. Wow - what a difference. But I stopped using it because the thermal cut-out kept kicking in - the UK ones don't have a fan across the amp circuits. Nearly crashed the band everytime the bass cut out. Surprising how bad rock sounds without bass! Having modelled what speakers the Ashdown has installed - Sica Z00653's - I found the cab design has a huge hump around 130hz and then drops away fast. That means the response is exactly what I'm experiencing - weak low E right up to about 15 frets above that - the 42 - 100hz range. The Delta I used helped a bit but also humped at around 100hz. The answer looks like a Kappa 15A in a similar size cab (22x20x13") as the combo speaker section below the amp. Although the 3015 would be even better the Kappa is half the price and since the amp is only 280 watts I think I'll get away with the cheaper chassis. The single Kappa will give me about 6db gain through 100-40 hx range over the 4x SICA 10"s. Any thoughts guys. Anyone had the same problems with the Ashdown MAG 410?