Tobias hit it on the head. You seem to be into specs and not sound. My 1st speakers were rated 20 - 20khz (BIC formula 4) and cost a whopping 219.00 pair in 1976. In 92 I replaced them with $800 Mission/Cyrus 782 monitors rated 70 - 20khz +/- 1.5db -6db at 50hz. Everyone who listened to the Cyrus thought they had more bass but what they heard was a clear bass - mid range - and high end. Granted I did eventually add a sub which got the sound I really wanted. I still have them today and love them. When the day comes for replacements so far I really like the Sonus-Faber Cremora's or maybe the auditors.
So I would look at new speakers first then an amp when the $$$ permit.
So I would look at new speakers first then an amp when the $$$ permit.