Well the first step is going to be describing (or better yet, providing a diagram or picture) of your room and placement of speakers, seating, furniture, doorways, any other openings, etc.
The room is a full 50% of any sound system, so trying to solve any speaker, subwoofer or amplifier concerns without knowing about the room is just a recipe for spinning wheels and wild guesses
There might be ways to address your room's acoustics or simply the placement of your speakers and seating within your room that will provide the changes you are seeking.
Once we have the room and placement sorted out, the next step is calibration of your equipment. Technically speaking, when your receiver's volume reads "0 (zero) dB" you are supposed to get 85dB at your seat with a THX reference level test tone. You are also meant to have 20dB of headroom with the volume set to "zero dB" so that you can hit the reference 105dB peaks for very short bursts at a time.
In truth, the number on the volume readout doesn't mean anything. It is a relative value. What you are supposed to do is set the volume to zero dB, play a THX reference level test tone (you can easily do this from any THX certified DVD or Blu-ray using the THX Optimizer found in the disc's menu), and measure 85dB on an accurate SPL meter at your primary seat. You are meant to use the "Speaker Level" or "Trim" controls in your receiver's setup menu to adjust each speaker channel's output so that you get the intended 85dB output with this scenario.
Once you have your speaker levels all adjusted in this way, you can set the volume where ever you like, according to your personal preference for loudness. an 85dB average with 105dB peaks is far too loud for most people's tastes. Most people prefer something closer to a 75dB average. So for most people, setting the volume dial to "-10dB" results in the desired loudness if they have properly calibrated their speaker levels.
If your room is too large or your seating distance is too far away, you might find that you have the volume set to "zero dB", you're playing a THX reference level test tone, you have the speaker level pushed all the way up to its maximum in your receiver's menu, and your SPL meter is still reading below 85dB at your seat. If this is the case, you require either more amplifier power, more efficient speakers, or both.
However, in most typical homes, it is rare to run into this problem. In fact, in many rooms, you will actually have the volume set to "zero dB", be playing a THX reference level test tone, you'll have the speaker level adjusted all the way down to the minimum setting, and the SPL meter will still be reading something louder than 85dB at the seat! If that is the case, you simply want to back the volume down 10, 15 or 20dB, adjust the speaker levels in the receiver's menu so that you get 85dB with the THX test tone at your seat, and then simply remember that your "new" reference level is -10dB, -15dB, -20dB or whatever it ends up being instead of zero dB.
So let's figure out your room, your placement and your calibration before we start worrying about bi-amping, new amps, new speakers or any of that stuff! A change of gear is not always the solution. Very often, simply optimizing the gear you already have can get you what you are looking for!
Hope this helps
