system has weak bass. any suggestions as to why?

System consists of oppo bdp-83se nuforce dvd player.synergistic research tricon analog interconnects connected directly into an adcom gfa555 power amp. speaker cables are monster 1.5s.speakers are mirage m7sis.amp. very recently repaired (had since new) input jacks replaced. some improvement, but bass is still pretty much still missing in action.replaced woofer in one speaker. made no difference.speakers are setting flat on carpeted concrete floor.both power amp. and oppo player are plugged into a power wedge 116. I suspect weak caps in power amp. but I am not sure. speakers and power amp. both set boxed up for 10+ years.amp. was then "brought up slowly" with a variac when it was initially powered up after its long sleep. I am cosidering a 2nd gfa555 to bi-amp speakers. this after talking to one high end (expensive) power amp. companies tech. who suggested that one gfa555 may not be enough amp. for the m7sis. any ideas as what to do next would be helpful .thanks
Just out of curiosity, are the speakers wired in correct phase? Just because the wiring looks correct doesn't mean it's right. At times I've needed to use a test disk to be sure.
also, replace the wire with different cables, system tonal balance can get out of wack surprisingly easy imo...
A number of things come to mind! How long are your interconnects and speaker cable? What is the impedance of the speaker and the db per watt meter of the speaker.

Putting the speaker on a solid surface or using spikes, will tighted up the bass, but not give you more.
Have you always lacked bass with this system or is this something new? If the answer is "always," I'd suggest that going direct from the Oppo to the power amp might be the issue. Some CD players (my Raysonic CD128 for example) do not take kindly to the absence of an active preamp in a system and sound generally bleached and undynamic without one, as I learned when taking my Raysonic to try in a friend's system that has a passive linestage. I also have a BDP-83SE and have never experienced weak bass from it via my Aesthetix Calypso linestage. Good luck, Dave
Is the bass weak everywhere in the room? ...or just in the listening position? Perhaps the listening position is location in a null bass point???

Try moving the speakers or listening position.

Just a thought...
LAK:The speakers are in phase. I reversed one speakers leads.Sound became diffuse. Bass became even weaker. Philojet:Tried zipcord 14 gauge 99.1% copper wire from home depot. Not much change. Surprisingly the zip cord did not sound to bad. Contemplating a double run of the 14 guage wire to see how it sounds. I also have another set of the Monster 1.5 cables that are N.I.B. However, I cannot bi-wire until I get a set of banana jacks due to limited space to attach speaker cables to rear of amp..Bullot: Interconnects are 1 meter in length. Speaker cables are 12ft. in length. The M7sis average approximately 6 ohms impedance. They are also approximately 87db sensitive/efficient. Dopogue: Yes this system has always lacked bass. I had it set up previously firing the long way in a 14X10 ft. Room. The sound was so disappointing that I boxed everything back up for the above mentioned 10+yrs. Weak bass included. I have an old Audio Research SP4 preamp that I put in line to see what would happen. Sound became Brighter on top with a softer/too soft midrange but no help on the lower end. Soulbrass: Due to space limitations (until I can finish cleaning my basement out). I am listening nearfield. The speakers are 2 1/2ft.out from the wall behind them. I have tried moving them from 2-5ft. from wall. The wall helps somewhat. Speakers are approximately 10ft. from both side walls. Rear of basement (direction that speakers are firing is asymmetrical). Speakers are 5ft. apart. Listening position is 5ft. back from and in between speakers. Thank You for your responses. I Will answer any replies as soon as possible.
I would recommend two things: Set up the speakers and your listening position EXACTLY (within an inch!) of what you get when following this guidance:

The other is to experiment with super cheap bass trapping. Go to HD / Lowes / etc and buy four rolls of insulation. Stack them two high and put them in the rear corners. This should improve the bass response noticeably.
how big is the room they are in? have you walked around the room to see if bass increases in other areas?

Cathode: I used a tape measure to get the speakers as close as possible to "Exactly" 5ft. Apart. I also measured as closly as possible 5ft. back from my listening position to form a 5X5X5 triangle. Both speakers are toed in 2". I am temporarily using this nearfield listening postion because I "fairly recently" moved. The rear of the basement contains boxes etc.. I am aware that these items can affect the soundfield of the speakers. But,I had hoped to minimze/eliminate the interference of "this stuff" by use of the nearfield listening position. www.cardas: I will try the use of insulation to see if the condition (bass) improves. You did not state a specific thickness. Is R-19 fiberglass sufficient? Also the speakers are positioned along the long wall of the basement. per your websites diagram F. Diagram B also applies. ( And yes my head did explode, Thank you very much!) Seriously though.The diagrams are very helpful. I appreciate your websites diagrams etc.. Thank you. Also, before I moved. This system was in a perfectly rectangular room. Approximately 10 X 14. 10ft. side wall to side wall. 14ft. the long way. The system lacked bass even in that standing wave prone room. Rayray8:I have the exact measurements for this room "somewhere". I will have to take them again.(sigh). Again the rear wall of the basement is assymetrical. A bar is located along part of it. An enclosed furnace and water heater is located right next to the bar in what would be the approximate center of the rear wall. The whole area surrounding the nearfield listening area is one open common space. (Aside from the previously mentioned stuff). There are no walls or dividers. Next to that area is an area that is currently serving as my bedroom. The irregularities of the "rear wall" makes the area almost impossible to measure. However, those same irregular surfaces also serve to break up standing waves. So its not all bad. However to answer your quwstion directly. The bass seems to drop off pretty much in direct proportion to the distance that I move away from the speakers. Also In general. Consistently he right speakers woofer appears not to be working as hard as the left speakers woofer. So in addition to the recommendations That I have received here. I am going to try reversng the leads to the right speakers woofer only. I will then see if this will help to correct the problem. Currently the speakers tweeters & mid ranges (rear mounted M.S.E.drivers) sound like they are in phase. (The m7sis are assymetrical front to back. Tweeters and woofers in front. M.S.E.drivers on backs of the units).I will try the various recommendations as time allows and I will let you know the results. Thank you.