As mentioned by you, the Swans M200MKIII are just "Powered Speakers".... ie Speakers with a built in amplifier (with Bass & Treble tone control in the case of the Swans M200MKIII).
Even as far as powered speakers go, the Swans M200MKIII are technically very Basic... One Power Amplifier for Each channel., ie thge Woofer and Tweeter are fed by the same amplifier, with the Treble Tone control used to obtain more treble.
It seems apparent to me that since the treble was very low in your speakers, and the tone control hardly increased the treble, the tweeters were probably damaged.
Better Powered Speakers will have separate amplifiers feeding each of the Drivers, ie separate amplifiers for the Tweeter & Woofer of Each Channel (a total of 4 amplifiers in a 2 way Stereo Speaker). Separate Amps for each driver permit an active (analog) electronic crossover to be used. A crossover separates the incoming signal for each driver, for optimal reproduction by that driver.
Powered speakers are VERY Basic compared to DSP Monitors that you mention in your subject line.
DSP (short for “
Digital
Signal
Processing”) processes the Signal in the DIGITAL Domain, where very precise & elaborate Signal processing is possible. A Digital Audio Signal is required for DSP, hence either the speaker will accept a Digital Input signal (SPDIF / TOSLINK, USB or whatever ) or take the analog input signal & covert it to Digital using an A to D Converter.
The Digital Signal is then Processed (DSP).
The Processed Digital Signal is reconverted back to analog before feedig it to the drivers.
Often separate DSP processing, (with separate A to D and DACs ) is used for each Driver.
The
KII Three is a Good example of a good DSP Active Speaker System. (Cost Rs 17 Lakhs+ )