Lets,for the sake of argument,throw these preamps into THREE catagories...
1. Cheap.aka: inexpensive...I would say anything under $400 is in this catagory.Most are built by a robot.The traces on their boards are thin and the values on the internal components is barely enough to cover the voltages required to do the job.The power supply will only be adequate.Many will have some features and AMAZINGLY will offer MORE features than a lot of the high-end critters.Sonically,in the hands of a very competent engineer, they will reproduce the sound of the source.What they wont do is work under heavy usage 24/7,the failure rate for a lot of intense input will be higher, and the aforementioned engineer will have to work particularly hard and diligently to attain depth of field and width in the sound.Yes it can be done but there will ALWAYS be something missing.A thorough investigation and graphing of the sonic curves and characteristics thereof throughout the complete range of sound, would go a long way in revealing the weaknesses inherent with gear of this nature. And much like the less expensive mics, there would be a certain tendancy throughout all the manufacturers offerings.Of course some will sound different than others.A different topology,more stages,a different way of making gain,different op-amps by different manufacturers etc etc..
2.Mid-range...aka...er mid-range in price...
This would be from the $400 to $700 but not inclusive as you can buy some single-channel lunchbox racked modules for the upper end of this price point.So for the sake of argument, lets say all inclusive rackmounted,pres and channel strips at this price.These are getting better as a lot will have iron in the system...ala TRANSFORMERS....this is not a kids toy or show about toys that become super-heroes...There will be a bit more upper-end engineering applied here but really not that far gone from cheap...The housing will be a lot heavier-duty and the power supplys will be getting closer to dealing with a contiuous high level of input and abuse.These units will last longer,retain their resale a bit better and generally have a sound right out of the box that can be attained by most anyone.When you crank the dials, there will be a more definate change in the sound.There will be features once again especially in a strip...LOTS of FEATURES...some you may never use or are only there to command a bigger dollar figure and dont work as well as a similar standalone unit might.But hey, you've saved money and headache time on hooking it up....These units are capable of reproducing the source sound as well as adding some of their own uniqueness to the signal especially if there are TRANSFORMERS involved.The 'engineer' will have less trouble getting his sound out of these and there will be a larger field and width to that sound.Excellent choices for those with a couple of years of doing this under the belt.
3.High-end...aka..da shizzits...anywhere from 6 or 7 hundred up to whatever the market will bear...I use 6 or 7 bills as a starting point because I believe that you can buy a used
API 512c module somewhere for this price.It may not be racked but it'll be available.
This is where it becomes a crapshoot. There are SO MANY boutique,and small mfgrs. building quality high-end pieces that actually work.And this also becomes a style kinda thing.Tubes?FET?IC's?Tranformers?In and Out?Variable Impedance at the front end?Vintage,Clone,or new revolutionary design?And The FEATURES!....One of the best sounding highest level audiofile type pres has a KNOB...and a SWITCH and ANOTHER SWITCH...and the just for fun ONE MORE SWITCH...thats it.Except for all the junk inside, it looks like a complete depantsing when you consider the price.Except that all your tracks will sound great.Novice,rookie,semi-pro,pro,...knobGawd...etc.This stuff will operate at levels 24/7...its supposed to.Sure gear breaks, but less seldom for the shizzit than all the others.This is industrial stuff...Its why a lot of the best designs have been around for umpteen years without a lot of changes to the theory,simply some upgrades to the components.Those who have not heard nor have used high-end gear really have no idea what thry're not hearing.Those who have upgraded to say a much better level of monitors and have gasped in amazement at the differenc,.....the highend electronic stuff does the same thing.Its a lot less work to get really good sounds...mic placement becomes an art as each move of an inch or so shows up as much or more than twisting a knob.High-end gear is not for everyone.Someone whos simply a hobbiest writing and recording at home can relax knowing that using cheap stuff is fine fir what they need.Someone who turns on the gear every week or two and piddles around with it can go there too.You are not violating any set rule about recording.Those who spend a lot of time on their own projects as well as others with an eye towards a true representation of their music had better look to the mid to highend for their gear.Thsoe that have a profession at this and have the electricity on ALL THE TIME had better buy the best tools possible.The maintainence costs alone to trying to do this with lesser gear is more than enough to make up the difference in initial cost per hours of uninterupted usage.You realize that the least expensive auto in the world to drive and maintain is a Rolls.
Thats all I wanted to say....I dont condem anyone for their gear purchases.I just hope that outlining what a person might expect of each level will help towards a more knowledgeable choice.Hell, if it passes signal, it works.What you do with it with the skills you have is a matter of choice.