This amplifier model is discontinued in 2024.  Kevalin Audio has one 211 tube design A-2500 SET Monoblock set, black chassis, new in box.  Payment by Bank Wire Transfer only.  Ship by FedEx Air Express Economy to USA and USA territories only.
The newest amplifier to the Allnic family is the A-2500, a pure SET design. It has a completely different circuit design from the former A-311M, featuring a new interstage transformer and larger power transformers on the stronger 2500 chassis platform.  At 20W SET, these will be the go-to amplifier for any speaker of 90 dB or greater efficiency.  The A-2500 is very spacious and outstandingly musical and emotionally engaging.  And - the bass presentation in no way left me wanting.  The 845’s low-frequency robustness is on par with my favorite power tube’s, the PX25..
 
A-2500 Monoblock Amplifier (Configuration at the factory only):
 
211 - 1st Stage 6CM7,  5R4WGA Rectifier and 211 x 1.  20W Continuous
Pure SET design.
 
845 - 1st Stage 6DR7,  5R4WGA Rectifier and 845  x 1. 20W Continuous
Pure SET design.
 
With the individual tube biasing, pairing is not necessary. Allnic circuit designs do not overdrive their tubes, and they tend to last a very long time. The M-2500 and A-2500 amps appear to retain this benefit.
 
To give you at least a rough idea of which of the “2500” monoblock amps might suit your requirements, you can find a handy calculator for amplifier power requirements for various speaker sensitivities and SPL at: 
 
https://www.crownaudio.com/en/tools/calculators#amp_power_required
 
Whatever choice you make, I am convinced you won’t be disappointed.  Both monoblock amplifiers are available with approximately a two-week lead time to delivery.  Introductory Price:  $18,000 USD.