Wow! I jumped on their website last week to order the matching stands for the Buchardt's and saw the S400's were on back order until September. I didn't know that was the order that was supposed to ship in June. Sorry to hear that. I had to wait a month or two for mine and it drove me crazy. They're worth the wait though. Just remember that they take a long time to break in (200-300 hours) and they like a lot of power (150+ watts). I'm currently feeding mine 700 watts RMS and they love it. Your crown amp should be a good match for them. The other preamp I had my eye on was the Schiit Freya. I've heard it's pretty good with different tubes. I settled on a studio grade dac as a preamp and it's very natural and neutral sounding, which is what I was going for overall with this system because I use them for music, gaming, movies, and TV. My other setup is the Buchardt S300's and a NAD 150 watt integrated that is only used for music. Overall the S300's are smooth, warm, very musical, and very forgiving of poor recordings. Almost sounds like it's a tube setup because they're so smooth and musical. The S400's have a much more natural overall presentation and are far less forgiving of poor recordings. Might want to try out a couple preamps to find what sound you like. First preamp I tried was harsh sounding with the S400's. I was happy I nailed it on the second try with the Mytek Brooklyn, but if not I was going to try either the Schiit or a PrimaLuna tube preamp. I'd recommend sticking with Class D to power them. It's better to find a high power neutral sounding Class D amp and let the preamp give it the sonic signature that you want. One last thing is the S400's are a little picky about how far away from the back wall they are because of the passive radiators. I've found 12 inches from the back wall is perfect for my room. 13 inches and they amount of bass drops off, and any closer than 12 inches and the resonant frequency gets higher. Spent a lot of hours moving them and critically listening to figure that out. With them the perfect distance from the wall and plenty of power, at most listening levels, they have bass that is flat down to 35hz, and drops off at 30hz. I've owned floorstanders that couldn't even do that. I sit about 3 meters away from them and have them about 3 meters apart and found that I had to toe them in just a little bit to get a proper center image despite the internet telling me to point them straight ahead. Overall though, very impressed with them. They do so many different things right and nothing wrong. Hope you get yours soon. Feel free to ask me anything anytime.
Mytek Brooklyn Dac+ | PS Audio M700 monoblocks | Buchardt S400's