If you are after quality, forget preamps with digital outs. Unless you are prepared to pay huge dollars, it's usually a trade of for quality vs price. Either the pre or the A/D or more often both will suffer to get the unit to an affordable price point.
And as has been debated here many times, the quality of the converters is secondard to the quality of you mics and preamps. It's the old "garbage in, garbage out" theory. If you put average mics and pres through quality converters, you'll just end up with enhanced "averageness".
OTOH, Putting quality mics/pres through average converters, you'll still end up with a quality sound.
So work on (IMO) preamps and mics now, and then converters later... if you really feel you need them.
For preamps now, check out the Vintech range...... You'll get
a Dual72 for around US$1350, or the new 273 for about $1800 including the PSU. Both great units.
Or the Sebatrons are worth a look also if you like the big valve sound, although this may not be desirable for acoustic stuff.