How much $$ do bells and whistles add to preamp?

I'm like you,  I prefer a "pure" preamp with the least bells & whistles, but ultimately the choice you make comes down to the sound, and not how many add-on's.

I'm pretty happy with my Parasound JC2.  The only add-on that you don't need is the Home Theater Bypass.   For me the HT bypass is a must have.  That actually limits my list of available preamps.

Anyway, good luck with your search.

I find myself in the camp that wants the DAC outboard, but the preamp is where the analog and digital meet on the way to amplifier and speakers. If you are considering a DAC an ‘extra,’ then you must be looking for an all analog system, which many people feel is the best way to go. My advice is to consider carefully which features you really need. For instance, I didn’t think I needed a balance control until I bought a power amp without one. I also became very frustrated with the types of controls avaible on some pared down versions of equipment. I’ll not name names, but rotating knobs are very convenient for changing source selections. Another issue is being able to view the way your equipment is set, how much volume? Any balance? Any tone control invoked? Which source is currently selected? You don’t know how much you miss this information, until you can’t see it, or you have to get out a flashlight, get down on your hands and knees and get your eyeballs two inches away from the face plate to determine the state of all the settings just mentioned. Again, I’m not naming names, but I have one in mind. If these things are important to you, in-home trials, careful thought, and lots of trials of inexpensive used gear seem in order. Just my two cents worth. And I agree with the fellow who said he thought adding a DAC adds $1,000.00 to the price of a $6,000.00 preamp. Of course, audio engineers will tell you that how many of these user controls are implemented can have a detrimental affect on sound quality. Choose wisely.

I made my own with a tube rectified polypropylene filter capacitor pi filter choke power supply for both channels (crosstalk due to low series equivalence resistance of the final 100 microfarad filter capacitor a small fraction of an Ohm) so I don't have to put up with future replacement of electrolytic capacitors. I used this to feed both channels of NOS #26 Arcturus triodes. The transformer for both cathode heaters has to be center tap grounded to prevent hum. Mundorf cathode bypass capacitors and a capacitor output to the main amplifier and you are ready to go. Also an Alps 100k volume control sounds much better than a stepped attenuator. 

It is every bit as good and probably better sounding than anything you would pay thousands of dollars to buy and it has none of the embellishments you don't want.