Before you splash out on expensive made to order panels. Take a look at rockwool rwa45. It comes in boards 50mm 75mm and 100mm thick 1200mm X 600mn but can be easily cut to size with a small saw.
My plan was to put them in their naked form until I was sure of their benefit form and then cover them with some coloured material of my choice using contact adhesive and some clever origami at the corners.
One pack of 100mm rockwool contains 6 boards and costs about £25
Sent from my M2103K19G using Tapatalk
Current system:
RPi + Allo Digione
Beresford Caiman Seg & Dorado powered by 15v Linear PSU
Transcendent Sound Mini Beast OTL
Amptastic Mini-1
Klipsch KG4.5 Speakers with Titanium Diagphrams and Sonicap Cap upgrade
110aH Leisure Battery powers the Mini-1 & Digione