Hi
Quick ... A little measurements plus correction by ear will extract more from your system than a lifetime of swapping components.
This preamble out of the way. The tools are NOT plug and play. You need to read some and be patient. Frustration is around the corner and despair not too far from it .. Pulling hair is optional.. Results can send you to heaven.. So ...
You need a laptop .. OS can be Windows, OSX or Linux, I use it with Windows.
REW Room Eq Wizard. REW , a powerhouse. And it is free. Take a good while to understand and use and a long time to master.Download on this
PAGE
Good but not superlative SoundCard M-Audio is your friend , nothing fancy their basic
USB Interface.microphone amplifier will do just fine.
Behringer ECM8000 Microphone , the
CrossSPectrum Calibrated one at $80
Some Sound signals available free at
Burninwave
A tripod
Patience, a willingness to learn and experiment. Persistence, lot of it else ..Hire an acoustician, this is involved and quite a bit so.
Quickly I would not rely on the iPhone for this purpose, results are likely to be unsatisfactory.
Lot of information at
that other forum
Results can be very good. You will appreciate your system more and shed a good deal of dogma along the way, or at least understand more.