Preamp Caps?Auricap,Mundorf, Hovland, jensen,solen

I have a preamp with only 2 Signal caps directly in front of two tubes shot right out to the amps, extreme simplicity and excellent sound. This is the first preamp that came stock with Auricap's I have owned or heard, most in the past have always had Multicaps, Kimber caps in my previous pre's. I can say I think the Auricaps are quite a bit better but not that expensive or the end all-be all that I understand. Now I have had some crossovers and a Preamp with Solen fastcaps in it, and they are the best in Bass I have heard out of all of them, not that it makes them superior just an observation. I have also purchased Jensens oil and put them in Tube equipment in the past, not bad but did not blow my doors off.. And Finally Hovlands, not my Cup if you know what I mean, I found them the most expensive and the least impressive, could be the mix of component used in, but whatever too dry for me. Mundorf is a little newer on the scene to me and I thought the Hovlands were pretty obscene in cost, however these are the new Cost and hype leaders from what I can tell today. I am considering trying the Mundorf Silver in oil supreme caps at no small cost to see if they are gonna create more magic than the Auricaps. . What is the character of this cap? I want very 3d and open yet still have some intimate warmth and very powerful bass. Is this a cap worth venturing over all the other explanations I left here? Needs a liquid sound, and get that fairly deep bass solen seems to be capable of for only a couple dollars a cap, cause I do not want to soften the already slightly soft Tube bass. Thanks to all that know about this tweaking and expereance with these caps . . Again its only 2 Caps, very easy to install so its hard to keep my hands off, but do not want to go backwards or waste the cause if its not gonna be very significant in this specific application, Anybody know of any good tube equipment or preamps using these mundorf super caps? By the way my tubes are Mullards NOS. Preamp manufacture would seem to be irrelevant here and yes I am pretty dang happy with the sound for the money already, but there is always more right 
Sherod, I went back to OIMPs bypassed with TFTFs in my deHavilland UV preamp about five months ago. I'm now using 2.7uf OIMPs bypassed with .22uf TFTFs. This combination blends seamlessly, and for the most part sounds like an all TFTF v-cap. That said, I did not have good luck with the 3.3uf OIMPs that I originally bought a few years ago. For some reason the 3.3uf OIMPs were much softer and slower sounding compared to the TFTFs and the tonal contrast between the two could be easily heard. I changed over to a single pair of 2.7uf Mundorf SIOs. I liked the Mundorfs for their resolution. However, at times the Mundorfs could sound lean and light on the bottom end, and a little matter of fact sounding. This was the main reason I gave the v-caps another try. In my system the OIMP/TFTF combination have a more expansive soundstage, the low end is solid and has some weight to it, tone is slightly lush, yet the detail and transparency is excellent.
Very interesting Tom. I am assuming that the original cap in your preamp was a 3.3 uf value. I'm curious why you picked a 2.7 uf OIMP with a .22 uf Teflon bypass. Is this because it matched the original cap value better? I'm curious what the input impedance of your amp is as well. Is it tube also? I currently have a 4.0 uf OIMP in my preamp output that replaced a similar value Hovland cap. The OIMP after break-in definitely lets through more information, but to my ears offers a little bit too much full-bodied sound. Another gentleman who does quite a bit of modifications and is familiar with the V-caps suggested that I bypass with a .1 uf V-cap Teflon. I did that and currently have about 315 hours on the bypass, and although the tone is a little less full-bodied, the overall sound is a little too tilted up for my tastes. I'm wondering if maybe I should go with a smaller OIMP as you did and try the Teflon bypass again on it. HMMMMM. very interesting.
The original caps in my UV were a paralleled pair of 1uf Russian PIOs and 1.5uf Auricaps for a total of 2.5uf per channel. What you are describing with your 4uf OIMP and .1 TFTF is similar to my experience with the 3.3uf OIMP. I tried a .01, .1, and .22 TFTF bypass with the 3.3uf OIMP, and although the .22 worked best, there was still a discernable cutoff point where I could hear the softer OIMP take over. And, yes the 3.3uf was a little to heavy handed in the bass, so that's why I gave the 2.7uf a try. The bass is more proportional, and overall the 2.7uf OIMP is quicker and more transparent. These qualities allow the TFTF to blend in better. Having tried both the .01 and .1 TFTFs, the .22 TFTF is not as tilted up on top, and has more body in the upper registers. The input impedance of my last two amps is 100k ohms, so the smaller value caps work fine. The deHavilland UV is a tube preamp.
I would like to comment that the above posters are going about selecting capacitors the "right" way. That is, to experiment with your specific piece of equipment and letting your own ears be the judge. There is no right or wrong in capacitor selection, it is a sonic recipe. Often a combination of two different caps.
Thank you Tom, for your detailed reply. I have tube monoblock amps that also have an input impedance of 100K ohms. As I understand the formula for determining the preamp output cap value, the lower the cap value, the lower the bass -3db roll-off point, correct? Also, Tom, when you put in the OIMP 2.7 uf caps, did you put them in alone and break them in before you put on the Teflon bypass caps or did you put everything in together and go through the long break-in period?