Normally I suggest high sensitivity speakers with big paper cone woofers for these situations, but in your case the problem could very well be the Monoprice amp. 35 watts/ch would normally be enough power for JBLs in a room that size, but that’s if the power is RMS, full bandwidth. I wouldn’t be surprised if the integrated’s RMS power is closer to 10 watts/ch in reality.
A low-efficiency bookshelf speaker like the KEF LS50 is likely to leave you worse off.
I’d probably put that $1K toward a better amp like a pre-owned Rega Elex-R or the Yamaha A-S801. The latter has a variable loudness control that will improve your low-volume listening regardless of partnering speaker, and you’ll have a great amp for when you do finally upgrade the JBLs.
A low-efficiency bookshelf speaker like the KEF LS50 is likely to leave you worse off.
I’d probably put that $1K toward a better amp like a pre-owned Rega Elex-R or the Yamaha A-S801. The latter has a variable loudness control that will improve your low-volume listening regardless of partnering speaker, and you’ll have a great amp for when you do finally upgrade the JBLs.