Don't see Thunderbolts come up for sale very often but I've been using REL subs for quite a few years with my Alon's/Nola's with terrific results.
You may also want to consider doing the woofer low-pass x-over upgrade on your Alon 1's. I just did the upgrade last night on my Alon 1's and it is a very worthwhile/performance upgrade and that observation is just a day into playing them.
You may also want to consider doing the woofer low-pass x-over upgrade on your Alon 1's. I just did the upgrade last night on my Alon 1's and it is a very worthwhile/performance upgrade and that observation is just a day into playing them.