Tube amps vs solid state for large speakers

What you really need to know is the impedance curve of your speakers, i.e. impedance vs. frequency and phase angle vs. frequency. The voltage sensitivity of your speakers will make them a marginal load for a low-powered tube amp, especially a SET amp. They might well be a very good match for a higher-powered tube amp, especially since they are a nominal 8 ohm impedance. There are good tube offerings from Cary Audio, Audio Electronic Supply, Antique Electronics, and some of the new Chinese amps like Cayin.

I haven't heard the AES Sixpacs but had an AES AE-25 Superamp, the DJH signature version. Great sound for the money, not the last word in tube warmth but more on the neutral side and good bass. The fun thing about the Superamp was trying different output tubes. I ended up trying over 20 types of tubes, each of which significantly affected the sound. You might be able to do this also with the Sixpacs, which have more power output and probably better bass.