SET amp recommendations for Zu Definition II's

I am currently running my Definitions with a Red Wine Isabella and 70.2 monoblokcs but wanted to add a set amp for variety. Wondering if anyone has found an amp tht really mates well with the Definittons. I was thinking an 845 but would appreciate any advice.
The RWA 70.2/Isabella sounded plastic/cardboard next to my Atma-Sphere amps on my Zu Presence speakers. Even the Art Audio PX25 smoked the RWA and made them sound like a toy amp.

I would call the Zu boys and get their take.

I sure would like to buy your Def's LOL.
845 SET amps excel with Definitions. Lots of choices driven by your budget. The 845 drives Definitions energetically, with bass definition appropriate to the speaker's deep response. There are significant differences as you climb the price ladder, but at any given cost stratum, an available 845SET amp will outclass a push-pull tube amp of similar power, or a PSET 300B on Definition 1.5, 1.9 and 2.0. You'll get wide dynamic range, SET subtlety in details, superior tone density and serious drive.

I use Audion Black Shadow mono blocks. They aren't inexpensive. But as you go lower in price, Mastersound, DeHavilland, Sophia, Tri, Dared, Melody and upstart Asian brands give you plenty of alternatives.

You then have ability to tune via tube selection. Input and driver tubes are influential, but since most of these amps are supplied stock with the cheap 845A tube, an upgrade to the affordable 845B is usually in order. The new Shuguang Psvane 845 may be an upgrade too.

There`s a recent thread by Afc which compared the Mastersound 845 amp to the Coincident FrankensteinMK2 on his Zu speakers. This may be of interest to you.
I would use the Coincident Technology Frankenstein's at 8 watt/channel and MSRP $5,000. Thy are as clean as a whistle and surprisingly powerful sounding. If one needs more tube power the Coincident Technology Dragon's at 70 watt are also great.
I have been using a Yamamoto A-09S, 300B amp for last 2 years with my Def IIs. I have had no desire to change. I did demo the Art Audio PX-25 before I bought the Yamamoto. I thought it matched up very well. I have seen them for sale here at pretty reasonable prices.
There are Komuro amps here on sale; should be good enough.
Schw, the Mastersound 845 amps are excellent. Lots of grunt. The Conincident Frankensteins are crystal clear. Both are great choices. I'd echo what Glory said. Sean Casey at Zu currently has my Mastersound Compact 845 on loaner duty. He'd probably be able to answer any questions as to how it performs with most any Zu speaker.
The Frankensteins will also run closer to 6K than 5K. If you go that route, you should strongly consider the upgrade to the Shuguang Treasure 300B tube, which puts it at about 5999. With that kind of money invested, going with the better tube is pretty much a no brainer in my eyes. Again, talk to Sean Casey. He'll be able to tell you better than we will. The Franks are "only" 8 wpc, but it's a damn strong 8 wpc. If you want to split your ears, you may want to go higher, but you likely don't need it with the Def Mk II's. The built in subs raise another issue with the Def Mk II's compared to my Essence. Sean will be able to answer those queries for you.
I use Audiopax Model 88 monoblocks on these speakers and have been very pleased with the results - certainly worth auditioning if you can.