Hello Angusat,
Player8's comments on the tonal balance of the PSB 5T and Image line relative to Axiom are very accurate, and parallel my own judgments of PSB speakers, which I've reviewed along with Energy, Axiom, Paradigm and many others for years.
"A slight warmth" results from a modest boost (a few dB, typically) in the upper bass frequencies over the range of 100 Hz to perhaps 500 Hz, whereas the Axioms (M60, M80) are typically smoother (no boost) or more "linear" in that range.
The "warmth" or lift in that region of bass (very typical of almost all Paradigm speakers) may add a kind of thickness or fatness to male vocals, a sonic trait that I find really annoying after hearing a more neutral speaker like the Axioms. I use specific recordings of male singers to test for that.
On first hearing, that "warmth" may prove to be flattering on some instruments--saxaphone, vocals, cello, double bass--but it isn't accurate. It's a slight coloration that gets annoying with long-term listening. The Stratus line of PSB (Silver and Gold) are much closer in tonal balance to Axioms and do not have that lift in the upper bass.
"More refined" means smoother with less coloration and fewer spikes or dips in the midrange and treble. For instance, PSB's Stratus Gold, which is very comparable in tonal balance to the Axiom M60ti or the M80ti, always had a bit of a glitch, or lack of refinement, in the upper midrange response. It made trumpet and violin sound a bit strident and I always noted it in blind tests with other speakers. Several expensive Thiel speakers also had a similar upper midrange stridency (much worse than the PSB) that I noted in tests. I don't know whether the Stratus Gold's was subsequently fixed.
I do know that the M60ti and M80ti have a very smooth, refined, and detailed midrange and upper octave response that does not have any "glitches" like the ones I described.
I haven't heard PSB's latest series.
In my judgment, the Axioms are smoother and more refined than the Energy Connoisseur series. The much more expensive Energy Veritas models are comparable to the Axiom M60 and M80 in overall refinement and neutrality.
Regards,
