OK. Some initial thoughts on these preamps.
Suncoast B2p
Big, full and punchy. Definitely tube tone. It does not have the breakup range that the SLO has which is totally fine with me. With a 12AX7 tube in the SLO I rarely turn the gain up past 9:00 or so on the SLO. The Suncoast B2p has a master dial and a volume dial for each channel. I like to think of the Master dial as a "headroom dial". Turn it up to create more headroom and then dial in the individual channel volume dials to taste. In other words, if you don't open up the Master dial a lot but turn up the volume dials, you will get more breakup. It's the wooly kind of breakup that is more like an amp on the verge of breakup or just over the threshold and obviously breaking up kind of feel. Not OD kind of feel which is great for me.
Each channel sounds different and both are highly usable. Overall, the B2p has a darker feel to it than a typical solid state preamp. Again, that's nice if that is your thing. The left channel is your Alembic F2B design. Flat is not all dials at noon.
Being able to combine both channels is killer. It is perfect for where you want to pop out of the mix, or boost overall presence for a chorus... that kind of thing. Honestly, I love running both channels together all the time. Big, huge, punchy tone.
Better than the SLO? Hmmm.... yes in many ways. And not in other ways.
BUT, the form factor It is bigger than the SLO. No cab sims. But, two tubes, two channels, more sound possibilities, and the breakup is more pleasing (to my ear anyway). If you have the SLO should you sell it and switch to the Suncoast? I'd say no. There is a lot of overlap. Given the choice of only having one? Hmm.... based on tone alone I'm going to go with the Suncoast.
The Suncoast lacks an onboard DI though.
Right now I am finding the Suncoast more flexible than the SLO with the dual channels and channel combine. I have it running out to a RNDI.
Marleaux Tonwerk
This one really surprised me. It is really, really good sounding. Very transparent (the opposite of the Suncoast). If you can't find a sound you like with this device.... well I guess you just don't know how to work an EQ. I think it is impossible not to be able to dial in something that sounds killer.
You have three EQ points for each frequency. And then you have boost and cut for whichever frequency you select. And you have control over both high mids and low mids independently. Huge EQ options. There are center detents for each EQ dial.
Input controls the input gain and corresponds with the LEDs monitoring how hard you are driving the input. There is tons of headroom. Output controls the output volume when using a typical patch cable connected to the output. When using the XLR out, the input control is how you control the volume out of the DI port.
Then you have a switch which sets whether the DI out is pre or post EQ and variations on that and what the footswitch does.
Definitely more on the modern side of things compared to the Suncoast. Definitely ads punchy and flair. Just real nice sparkle and punch. Perfect device to deal with room dynamics.
It has a headphones out too which is nice for practicing and dialing in your sound. No AUX in though.
I really like this one too.
Meridian Trinity
This is from the Meridian Guitars company out of Italy. This one looks real cool. Sort of retro. The VU meter is pretty slick and monitors your input gain.
From a tone perspective it is somewhere between the Suncoast and Marleaux. Definitely some inherent tone coloration but not as tubey as the Suncoast. The mid range sweep is great. The switch on the left determines which EQ point the Bass EQ dials and the right switch does the same for Treble. Love that feature. There are center detents for each EQ dial.
It has XLR out which sounds great. The footswitch on this one mutes the pedal. If you use the preamp as always on and last in your chain, then the footswitch essentially mutes your signal. I like that.
It is less neutral than the Marleaux. Adds some nice "umph" to your tone. An always on type of device.
I really like this one too.
I need more time with all of them to decide if all of them are keepers but I will say I was not let down with any of these. Sometimes you can get a new effect and know pretty much right away that it is not for you. Not so with any of these. They are all great in different ways. I will definitely be selling at least one of these, probably two.... just so I can try others.