I’m no fan of ports, if so, front only.
Those speakers ought to have darn good bass without subs. Perhaps tighten the bass by closing the rear ports.
Did you ever try Dynaudio’s Port Plugs? Or blocking/stuffing them yourself?
Dynaudio’s Speaker Positioning Info is very informative
https://www.dynaudio.com/discontinued-models/excite/x44/support/manual/en/positioning-installation excerpt:
"Dynaudio speakers are designed to perform at their best when positioned as far from any walls as possible. Ideally, try to aim for a minimum distance of 50 cm (18 in) from each speaker to any wall. Diagram 3 illustrates room boundary distances.
Diagram 3: Distance to walls
Speaker positioning – using port plugs
If your Dynaudio speakers have reflex ports and are supplied with foam plugs, these can be fitted to reduce the bass emphasis that may be apparent if the speakers are placed close to room boundaries. Some Dynaudio port plugs can be split to provide optional levels of bass volume reduction. For mild bass reduction, fit only the outer foam ring by sliding it in the port tube so that it sits just inside the flared port exit – making sure it retains its shape to minimise airflow turbulence. For more extreme bass reduction, fit the complete plug so that the port is blocked. Diagram 4 illustrates the use of port plugs and their effect on speaker frequency response."
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After closing the rear ports, ’tightening’ the front bass, then, discover if you want ’lower’ bass (not ’more’ bass).
IF so, I recommend a ’stereo pair’ of front facing self-powered subs located adjacent to the mains. Both the fundamentals and their overtones, i.e. 36, 72, 144 ... provide directional information, you will know where the bass player is standing!
Even if you have plenty of bass at normal listening levels:
For low level listening, due to our ear’s variable characteristics, you need to boost the bass to maintain it’s volume relative to other frequencies,
the easiest is a fletcher munson filter, progressively increased bass as volume diminishes.
https://en.wikipedia.org/wiki/Equal-loudness_contour
Proper setup, point of engagement, of ’loudness’ (stupid name) filters is important, many misuse it.
