IME, subs do 3 or 4 things by design (depending on how they're implemented) and a fourth by default:
1) They provide sub bass below 30hz (some say 20hz, as a practical matter I'll say 30hz). To buy a sub that does this well is a very expensive proposition - I'd argue that it's well above your budget. The good news, for a music only system, you don't need this. Even pipe organ recordings have little meaningful info down here (at least the ones I own). By the way, even the subs providing sub bass poor performance (i.e. 30+% distortion which is pretty common at these frequencies) may provide a sense of enhanced sounstage. It's a bit of a mystery to me, but I noted this effect even when I used subs that were "bad" for sub bass.
2) They can provide bass below 100hz. You can actively cross a sub(s) to replace the bottom octave of your monitors. A good one will probably improve this portion of the frequency range. This, of course depends on the monitor in use.
3 - maybe) Depending on the main speaker, even a bad sub will remove the bass load from your main speaker and allow it to perform better, if you actively x-over high enough.
4) A sub allows bass placement near the walls, (and/or digital room correction for some models) which will almost always provide smoother bass performance than even a super expensive speaker placed out in free space.
!) The thing subs do by default is create a real task to achieve smooth integration. There are tools to help you get this result, but they're way over budget.
Bottom line: At $1K (if you're careful with your choices) and (way,way if you like) up, a sub can do great things. At less than that budget, they're much more likely to do harm than good.
IMO and IME.
Marty
1) They provide sub bass below 30hz (some say 20hz, as a practical matter I'll say 30hz). To buy a sub that does this well is a very expensive proposition - I'd argue that it's well above your budget. The good news, for a music only system, you don't need this. Even pipe organ recordings have little meaningful info down here (at least the ones I own). By the way, even the subs providing sub bass poor performance (i.e. 30+% distortion which is pretty common at these frequencies) may provide a sense of enhanced sounstage. It's a bit of a mystery to me, but I noted this effect even when I used subs that were "bad" for sub bass.
2) They can provide bass below 100hz. You can actively cross a sub(s) to replace the bottom octave of your monitors. A good one will probably improve this portion of the frequency range. This, of course depends on the monitor in use.
3 - maybe) Depending on the main speaker, even a bad sub will remove the bass load from your main speaker and allow it to perform better, if you actively x-over high enough.
4) A sub allows bass placement near the walls, (and/or digital room correction for some models) which will almost always provide smoother bass performance than even a super expensive speaker placed out in free space.
!) The thing subs do by default is create a real task to achieve smooth integration. There are tools to help you get this result, but they're way over budget.
Bottom line: At $1K (if you're careful with your choices) and (way,way if you like) up, a sub can do great things. At less than that budget, they're much more likely to do harm than good.
IMO and IME.
Marty