Best bookshelf monitor under $1000 new or used.

The Paradigm Studio 20 v4 are a great monitor for the money. Can be had for $600-$700 used here on Audiogon. They received an excellent review in a recent issue of Stereophile. The Studio 20 v3 is also very good, and can be had for slightly less.

The Silverline Minuets blew everybody away at the NYC HE Show using a garage sale CD player and a modestly powered Monarchy DAC/Integrated (so I guess you'd have lots of amp options with these speakers). That modest system managed to physically put a standup bass fully in a good-sized room that you would have expected from a good 3-way floorstander. Everybody's jaw was on the floor, so if you want to be amazed they're probably worth a look if in your price range. I'd also consider Epos.

quad 12L active, biamped, electronic crossover. NO amp expense, highly reviewed quad l series, less than $1000. I have personally commpared to many other speakers and is my speaker of choice at the moment

New AER Pisces MkIII - about $300. You must have good stands too.

You can drive them by Dynaco 70 or any other low power tube amp (20 - 50 wpc) - and you are in heaven! No subs needed.
Try some Chineese based on EL84 tubes...
Solid state.... I don't like cheap solid state...may be NAD, some British electronics - again 50 wpc is enough

KING OF THE MONITORS: DYNAUDIO!

They really are impressive. Check out the 140's or the 52SE's. HUGE bang for the buck. Very neutral, detailed and fun in every sense of the word. I have looked into NHT, Quad 12L, Monitor Audio GR10, but nothing moves me like Dyn does.