Welcome!
You didn't mention the three most system components, your ears, loudspeakers and the room. Sorry to break it to you but at your age your ears are pretty much shot, probably can hear little above 1,000 Hz (extrapolating from my recent hearing test at age 65). 99% of hearing aids only try to recover up to 8,000 Hz (for conversational use). There's was a recent thread here at Audio Circle about hearing aids. I'm trying out a $4000 pair at my wife's insistence and so far not impressed. Still miss some of what she's trying to tell me (the main reason for giving them a try). But in general she's a poor communicator, assumes I mind-read, starts mid paragraph/mid sentence, and waits until I'm out of the room before speaking.
Loudspeakers have changed quite a bit in recent years. The move is towards active design thanks to dominant studio use. Actives use sophisticated low powered crossovers to drive one channel of amplification per driver, all contained within the speaker cabinet. Many actives also include advanced room correction software. Most actives are 2-way monitor designs as the matched amp/drivers are much more efficient in a multitude of ways. So sorry your loudspeakers and Hafler amp is essentially obsolete. By the way, the internal amps used are usually newer highly efficient class D solid state designs.
Lots of research has been done to study room acoustics. Suggest reading Floyd Toole's "Sound Reproduction" (either edition). In it he demonstrates that all rooms have inherent bass peaks/dips and the use of multiple subwoofers is the best solution. In general avoid small, square, uninsulated rooms that share functions with others. For instance I have an 8ft x 13ft x 21ft well insulated man cave that cost virtually nothing above the cost of finishing off that portion of the basement. The room dimensions follow Fibonacci ratios, same as the ancient Greeks used for their stone temples to control echos.
