With very small speakers 4 inches woofer i prefer rear porthole ...Because it is easier to redesign his volume /neck ratio in a more nuanced and complex way ...
The result i reach with this modification elevated the performance to an incredible level ... near 50 hertz strong, no boominess, clarity all along the frequencies scales ...I modified also the wave guide of the tweeter for my position ( 3 feet ) resulting in a soundstage extending way beside each speakers with frontal and rear death...
All that with 150 bucks well reviewed but modified active speakers but also damped against vibration and resonance with my own device which is concrete block with over it a sandwich of many different materials ( oak plate-bamboo plate- granite plate-shungite- plate cork -plate sorbothane plate ,alterning in this sanwich more softer material with the harder one for an optimal coupling-decoupling chain ) and the damping is with tuned load of concrete block over them also ... All my connectors are shielded with my recipe (shungite plate)...
I can assure you save for deep bass under 50 hertz for sure, i lack nothing and my active speakers driven by a tube preamplifier beat all headphone i heard save my top best one and reference one : the only working hybrid AKG K340 optimized and modified which go near 25 hertz clear ....
Some are proud of their 100,000 bucks system 😊... Me i am proud without reservation of my 1,000 bucks one😁 Speakers + NOS dac + tubes preamp and tones control and a new amplification ( Sansui alpha) dedicated for the headphone only with his own battery dac ...
I only need the BACCH system of filters as upgrade ... Anyway even without them i listen a soundfield with differential space qualities ( i mechnically decreased the crosstalk ) in my speakers and out of the head soundfield with the K340...
All this to say rear porthole are not bad at all , if you know what to do ....😊
Ported speakers might work if the port is in the front, but if in the back, trouble ahead