Best sub for Sony dg910?

I see you made it over here to the sub forums!

Matching a receiver to a sub is really not a concern. What sub is a good choice for you depends on a great many other things however.

In particular:

What is your room size? LxWxH
Does it open into any other rooms? Doors, etc.
Do you have neighbors? Are you in an apartment?
Do you have size restrictions? Some subs can get quite large.
Do you aesthetic requirements? Wood Finish, Piano Black, etc.
Are you concerned with overall output (most SPL), or would you like a smaller sealed design?

With answers to these questions, we can make our suggestions.

But honestly with around a $300 budget there are only going to be a few subs worthy of mention around here.

Elemental Designs A2-300
Premier Acoustic PA-120
Cadence CSX-12 or maybe CSX-15
HSU STF-1 or STF-2
and maybe even the Dayton Sealed 15" Kit from PE.

Good luck and check the stickies at the top of this forum for FAQs with regards to choosing a subwoofer.

The PA-120 is probably one of the better subs for home theater in the under $300 category, though it's rep is it's not as "musical". The Velodyne VX-10 and some of the Infinity's I believe have tended to be recommended as more musical in the inexpensive sub category, but the Velodyne won't go as low as the PA for home theater. So if you want the emphasis to be on HT, go with the PA, if you want more balance with musicality but a bit less punch VX-10. Now, you will immediately get people on here who insist that you really need a sub that goes to 5Hz because they think you really have thousands of dollars to spend and are just being cheap, but assuming you know your budget and thousands isn't an option, those options would probably suit you =). The PA seems to be going for $258 shipped or so, the VX-10 is the bargain at $189.

I took a look at the back of the DG910 and it just has a single subwoofer "preout" like most receivers. You can split them with RCA splitters for more subs, but when you said it had outputs for 4 subs (that is extremely unusual, as even very expensive receivers only have 2 subwoofer preouts), I'm not quite sure what you were looking at.

The speaker level inputs you noticed on the back of some of the subwoofers are just that. They allow you to hook up a subwoofer to a receiver that doesn't have a dedicated subwoofer preout like yours. This works great with old vintage two-channel receivers for example.

Most of those subwoofers listed still have two RCA type inputs. Most people get around this by running a RCA Y-adapter or just running their single subwoofer preout cable to only one of these inputs (usually the left for some reason).

With your budget in mind, there are few here who would argue that the A2-300 will be your best bet. The only downside to this subwoofer is that they are built to order, so you might wait a few weeks before it's delivered. The other downside (and most ported subs for that matter) is the size. Check the measurements. Make sure it will fit, and plan on trying it in as many different locations as you can within your room.

Placement is everything with a subwoofer. I'm still not quite sure I have the best location possible for my CSX-15 in my room. But there are only so many places I can put such a big sub.

If you order now, like tonight before midnight eastern I think, you cant ge the Outlaw LFM-1 compact for $319 shipped. It is normally $399 plus like $60 to ship.