Welcome!
Suggest putting emphasis in the design of the room. Avoid small/squarish and poorly insulated. When we built 16 years ago I got a dedicated basement room: 8ft x 13ft x 21ft (Fibonacci ratios) to minimize echo. Insulated staggered stud interior partitions (even adjoining storage spaces), insulated exterior fiberglass door with weather seals, insulated/lined flexible ductwork (can't hear the furnace). With cheaper carpet ended up being the cheapest square footage of the house. The only mistakes were in the ceiling (using recessed lights and the builder refusing to suspend the ceiling). As it turned out my room is very similar to Earl Geddes' room, who is another renowned acoustician.
Since then added 3 tall bookcases on side walls that act as "casual"/adjustable diffusers, 10 GIK 244 2ft x 4ft absorption panels (recommended but unfortunately would be expensive to ship to Australia - the magic ingredient is Owens Corning 703 high density fiberglass), and 3 subwoofers ala Floyd Toole (recommend reading his book "Sound Reproduction"). In my room the panels are minimally effective but highly effective in lesser rooms. The multiple subwoofers are the best way to tame inherent in-room bass peaks/dips which can be +/- 30 dB. Good luck and be sure to post pictures of the room when done.
