My expertise in audio ? 45 years . Have had a lot of systems , tubes and solid states so I know a little on the subject . First , changing the amp won't help much . That being said , take heed , be sure it is a high current design . That helps and makes a difference . But more importantly the speaker . I'm sure there surely are many options . One of them I can easily recommend which always impressed me by how clearly and dynamic they sounded at low volumens are the LSA 1 reference . They are discontinued now but pop up every so often on Ebay , Usaudio and audiogon .
Not only do they sound good at low volumens but great at any loudness . I bought mine at Ebay for 300.00 . They were 1,300.00 new . Highly recommended .