Prima Luna or sonic frontiers or audible illusions

I have an audible illusions 2d. It has served me well for many years. But, it seems I have the upgrade bug of late. I am looking to increase the imaging if possible of my system and am curious if upgrading to the modulus 3a would be a significant improvement. Or, would I be better served with a sonic frontiers sfl1 or line 1/2? Lastly I have to admit that the prima Luna prologue is appealing bc of the exposed tubes. Not sure on the sound though...any advice? Any other choices that have the tubes on display?
I love my SF equipment for two reasons. It all sounds great and is dependable. Second, Chris at Parts ConneXion who designed most of the SF has a full repair and upgrade program. He is knowledgable about the equipment and the TUBES that work best. His upgrade program offers his recent best mods based upon him using any and all parts that are now available. For me, the upgraded stuff is a joy and I have had a part in chosing what works for me. Contact him and he will give you his opinion on what would work best for you.

I have to agree. SF preamps are excellent, even the entry level ones. Given your 3 choices I would definately pick SF.
I would take the Modulus 3A first. I own a 3A and the 3B preamp so I am biased. Second choice would be the Prima Luna. I have heard a lot of their equipment and like what I hear. Last would be the Sonic Frontier as the line is no longer made. Even though the Parts Connection can service it, I personally wouldn't touch it. You should be able to pick up a nice 3A for a grand or less and it has a great phono section too.
I would have to agree that the Modulas is by far the better sounding preamp of the three, even if your main listening is done with your digital front end,with that said the phono is why you buy the Modulas 3A or 3B. There is a factory refurbished 3A for sale now on Audiogon with warranty for a little over 1,500.00 and it has the John Curl phono boards. I currently run the 3B with the JC board, had it built 4 years ago to replace a Modulas 3A. Also have a Lamm LL2 line stage coupled to an Allnic 1500 phono that serves in the same system, not better than the Modulas just different. Tooblue.
I have always heard good things about Chris and sonic frontiers, but I would love to know what ya'll hear as sonic differences bw each pre. The prima is the most tempting bc of the exposed tubes. Aesthetically I just like the exposed tubes. However sound trumps looks by a large margin. Is the prima going to image and soundstage like the ai or sf? Is the sf or upgraded ai going to best my older ai? By what margin? I find it hard to believe I have already reached the dollar/cost threshold...
I purchased an Anthem Pre One by Sonic Frontiers to replace a Nakamichi. The phono section was very noisy despite the Johnson Bros. suggestions of numerous tube replacements. Their local dealer had to eat the cost and for an increase in price I selected the well reviewed AI M3A. After stone walling their retailer, within weeks the Johnson's took their Pre One Phono off the market releasing the non phono version only.

The AI had very limited attenuation. Four or five clicks of the stepped attenuators before it was too loud or too soft regardless of switch settings or main board revision. In a very short time the dual mono attenuation became a pain. My family hated it. The attenuators wore out in a few short years and despite an absolutely definite two week estimate for the repair it took over four months.

In my experience these are two of the shadiest manufactures I've had to deal with.

I'd suggest looking for an older used VAC pre.
Check out Rogue Audio,it has the tubes displayed!
good call on the phono section...i don't need it. i'm a digital only guy. i know that is sacrilege, but it is what it is. a line stage only will serve me just fine. unfortunately i seem to recall reading that the modulus performed better than the linestage.

i have had good luck w/ my ai 2d, i hate to hear that others have had bad luck. it's the outboard power supply and dual mono that makes the ai appealing. similarly the prima was attractive b/c of it's dual mono configuration.

i looked at the vac preamps. not sure how the standard stacks up, but i can't afford to spend 3-4k on a used pre. 2k is the top of my budget unless there is something that will be truly earth shattering.

can anyone speak to the specific attributes of the aforementioned pre-amps? my 2d throws a big soundstage, but the imaging is a less pinpoint.

thanks for the advice.
I had a 3a and a Jolida Fusion. Rotated them in my system for a couple months. I sold the 3a. This was primarily due to not using the phono stage and thought it a waste to run the phono tubes. It sounded great however. The Jolida is a fine pre for the money ($1295 new and can be purchased with upgrades which still keeps the price below 2K. Not much to look at compared to the Prima luna. Not heard that pre, but would like to compare against the Fusion.