Alfred,
One thing that hasn't been mentioned is that nobody will want to buy your modified speakers in the future. Selecting drivers/crossovers is a very interactive process, and is tricky to maximize without a lot of experimentation & knowledge. If you decide to modify them you'll have even more money wrapped up in them while the resale is simultaneously dropping through the floor. A potential buyer is likely to view the whole process as a huge red flag. If you change them you better want to keep them. It's probably not the best investment.
I suggest you sell them and combine your resale proceeds with whatever you would have spent on upgrades to finance the new purchase. I'd suggest a used or kit pair. There are many great kits from the sources listed previously. I've owned Madisound MDY-4's (they won't have the bottom end you're looking for), but they offer several other great options (I was always partial to the Dynaudio kits). I went with North Creek Music Systems (Scanspeak drivers and NCMS crossovers are amongst the best of the best) for my current setup. You owe it to yourself to check out the kit option. The other best bang for buck is to pick up a pair of whatever you've heard and liked used. A suggestion for small speakers with suprisingly good sounding LF (so long as you don't play them too loud) and great midrange/HF is the Totem Model 1's.
Best of luck.
One thing that hasn't been mentioned is that nobody will want to buy your modified speakers in the future. Selecting drivers/crossovers is a very interactive process, and is tricky to maximize without a lot of experimentation & knowledge. If you decide to modify them you'll have even more money wrapped up in them while the resale is simultaneously dropping through the floor. A potential buyer is likely to view the whole process as a huge red flag. If you change them you better want to keep them. It's probably not the best investment.
I suggest you sell them and combine your resale proceeds with whatever you would have spent on upgrades to finance the new purchase. I'd suggest a used or kit pair. There are many great kits from the sources listed previously. I've owned Madisound MDY-4's (they won't have the bottom end you're looking for), but they offer several other great options (I was always partial to the Dynaudio kits). I went with North Creek Music Systems (Scanspeak drivers and NCMS crossovers are amongst the best of the best) for my current setup. You owe it to yourself to check out the kit option. The other best bang for buck is to pick up a pair of whatever you've heard and liked used. A suggestion for small speakers with suprisingly good sounding LF (so long as you don't play them too loud) and great midrange/HF is the Totem Model 1's.
Best of luck.