Unfortunately, due to the 64 Hz crossover frequency of the subwoofers, the sub output of the Wiim is too quiet when you want to listen at a low volume, and my monos Amp don't kick in.
Where does the 64 Hz crossover come from? Is that a fixed frequency built into your subwoofers? Which make and model? If they are DIY designs, wich components have been used?
As a reminder, the Wiim output is mono and above 80 Hz it is simply a disaster.
WiiM does not enforce any crossover frequency on you. You can freely select the frequency between 30 Hz and 250 Hz. And no, a crossover frequency above 80 Hz is not
necessarily a disaster. It all depends.
Did you notice that you can individually enable or disable the high pass filter for the passive loudspeakers and the low pass filter for the active subwoofer(s) in the WiiM Home app? You can even disable both at the same time (in the rare cases this makes sense). Additionally, you can configure the subwoofer level from -15 dB to + 15 dB. The correct value must be found individually for each and every setup, because it depends on the main speakers' efficiency, the subwoofers' efficiency, and the subwoofer amplifier's gain (and volume setting). With typical subwoofer plate amps, the subwoofer level often even depends a lot on the crossover setting selected on the plate amp (which is the fault of the plate amp). There's nothing magically right in the 0 dB setting. Finally you can adjust the time delay between the main speakers and the subwoofer(s). No individual correction for a right and a left sub, of course, since it is single mono output, as you already know.
Pre gain at -3 dB, because at 0 dB, the volume 22 setting is already at 80 dB volume on the main speakers.
Pre-gain has nothing to do with matching the main speakers an the subwoofers at all, that should be clear. But yes, with very high efficiency speakers the sound pressure level can be quite high at medium to low volume level settings, in particular with streaming sources. Again, this is not related to subwoofer integration. If your intention is to lower the output volume of the WiiM Amp Ultra for all sources, not just for one or two, then it's more efficient to set a volume limit (Lautstärkebegrenzung) in the audio settings (Audioeinstellungen) instead of reducing pre-gain. The name might seem to imply otherwise, but this is not some kind of limiter. You retain 100 steps for the volume setting, but the output power is reduced proportionally. If you are looking for a 3 dB decrease in sound pressure level set the volume limit to -5 dB. A setting of -10 dB will result in a 6 dB less SPL.
When I listen to songwriting music or similar genres where nothing happens below 70 Hz, I switch off the mono speakers and increase the frequency of the subwoofer. i.e. above its crossover frequency, this overlaps with the main speaker and, as it is a mono output, it becomes critical with the localizability of the woofers and they run too high, a bowed double bass or bass drum are happy about the fat sound.
The problem lies in the electrical range.
The match between the Wiim Amp Ultra and the monos does not fit.
I got the Wiim Amp Ultra for the Wiim Ultra because of the better DAC implementation.
What are the "monos" or "mono speakers" you keep referring to? Your subwoofers? If so, it would be a lot easier if you would simply call them like this.
Also, what's the thing with your Heco Zweiklang? These are certainly not dipole speakers so not what you described as your speaker system. Are you running two pairs of stereo speakers with the same dual subwoofers? How do you switch between them?
The problem lies in the electrical range.
The match between the Wiim Amp Ultra and the monos does not fit.
I got the Wiim Amp Ultra for the Wiim Ultra because of the better DAC implementation.
Which electrical range? What actually
is the problem? I still struggle to get it.
Are you actually asking for help with your setup (in which case you will find a bunch of very knowledgable community members here) or did you just come to report that something was wrong with the WiiM Amp Ultra subwoofer output (which is simply not the case)?
If the former, it would also be very helpful if you would start your very own thread describing your own situation in a matching subforum instead of hijacking other people's threads. We are now discussing your WiiM Amp Ultra issues in a thread that's been started for a WiiM Pro in the appropriate forum, which is a totally different animal. Nothing, really almost literally nothing that is important when setting up subwoofers with a WiiM Amp Ultra is even comparable to what is required using a WiiM Pro.
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