What does a subwoofer solve?

Luxman M900u.  Very happy with the new amp, except for disappointing bass performance.

My experience with Luxman was the same. That was in the late 80's. I hated every minute with the Lux. It had no bass line , just a constant thump from the bass drum. And it didn't sound correct.. I  cringe even today when I see the name yet it seems to be popular. I think this is because there was a great push for midrange clarity back in the 80's at the expense of the bass. Indeed the bass was often over blown prior to that. And maybe the mids weren't as prominent as many are today. But  the problem with change is often the pendulum swings  to the opposite extreme.That's where we are today IMO

IMO, the question becomes can the subwoofer put out what is Not fed to it? NO. And if you have the same issue that I had, where there was very little to no bass line at all, then I don't know if the sub will give it to you.. I sold my Lux  within 6 months. Good luck

BTW a good sub will enhance all the frequencies of the music and make the main speakers sound bigger.

Dear @lldd : " BHK 300 mono blocks. The bass they provided for my Monitor Audio PL 300ii speakers was exceptional. ..................... Luxman M900u. Very happy with the new amp, except for disappointing bass performance. "

Well, both amplifiers are way different designs Where the BHK is an hybrid design with MOSFET output devices the Luxman is all SS design with bipolar output devices.

I think that you are comparing that " bass..exceptional " that in reaslity is more a colored/distorted sound coming from the BHK against the accurated and less " colored " Luxman design that between other characteristics play in pure class A for its first 12 watts that due to the Monitor Audio specs permits that you have in reality better sound with than with the BHK. Yes, I know that you like more that frequency range in the BHK but this fact is other kind of matters.

In the other side you are talking of " bass " in your speakers when the crossover in the MA comes at 500 hz and the speaker goes down around 32hz. It’s really dificult to to pin-point true bass range when the woofers/ports handle that really wide frequency range. Btw, you can play/test too with ports open/closed and the like and due that both amplifiers are so different you need to play too with little changes in the speaker position in your room: backward/foreward and its angles at your seat position you are accustom to. Even you can play too with changes in your seat position.

My take is that that Luxman is a superior amp but you are the best judge about because you know what you like.

Looking that wide woofer frequency range ( 32hz-500hz handled at the same time and those " long " excursion of the woofers say at 35hz affects directly to the remaining frequencies handled by the woofers: increment its distortion levels. ) that 500hz at the speakers crossover and other than the true bass frequency range adding a pair of powered subwoofers crossing at around 80hz using lo and high pass filters will improves the overall quality listening room/system against what you have to day and against with what you had with the BHK due that when you liberates the speakers woofers of bass frequencies below 80hz suddenly your main speakers will goes way lower in its today high IMD levels. This is the main positive contribution/improvement of subwoofers with the speakers you own and additional to that now you will have the true bass range handled by woofers and amps with dedicated units that were designed in specific to fulfill the true bass frequency range reproduction needs. Your main speakers will performs and shines better than ever, its clarity/transparency/dynamic/headroom and lower colorations will be amazing to listen it from top to bottom.Obviously you need a good integration of those subs where what you listen be a unity.

You do not mentioned if your system has a room treatment that almost always is mandatory for better quality performance levels.

Regards and enjoy the MUSIC NOT DISTORTIONS,

R.

My experience with Luxman was the same. That was in the late 80’s. I hated every minute with the Lux. It had no bass line , just a constant thump from the bass drum.

I can’t comment on something 40 years ago, but in my recent memory, of the past 3 years or so I’ve never ever heard the Luxman’s be bass shy.  The Luxmans I know of have extension in spaces both in the treble range as well as in the bass.  I am more likely to believe the BHK lacked treble, and that Luxman is more well balanced. 😁

But seriously, if the effect the OP describes is so severe it makes him want to suddenly add a sub I’m going to question whether this is really due to an amp swap. Room acoustic issues like adding more reflective elements in the room, or taking away bass traps are the sorts of things I’d suggest first. Next, if this really really is happening, swap your cables for some Mogami 3106s. On my Luxman I had to turn the bass DOWN after I put this cable into my system.

OP,

I think that it is great that get to audition a sub or two in your listening room. I am anxious to find what you think.

According to manufacturer specs M900u balanced input impedance 34 kΩ and BHK 300 mono blocks balanced input impedance 200 kΩ. If the preamp has high output impedance that may explains the Luxman doesn't has enough bass.