Positioning Of Vienna Acoustics The Kiss Loudspeakers

I would like some help with the appropriate positioning of my Vienna Acoustics The Kiss loudspeakers please.

I have had them for a while now and they were positioned correctly. I recently changed DAC’s to the PS Audio Direct Stream. With this I find there is a more open sound, more air and layering of instruments. However, the downside of this is there is some sibilance in the treble and upper mids and an overall leaner sound with less weight and midrange richness.

To remedy this, I tilted the head of the Kiss with the coincident midrange and tweeter towards my ear by quite a bit more. Prior to this it was tilted higher away from my ears and the listening axis. I had tried moving the speakers further out/ closer to the wall behind them, more / less toe in, swiveling the music centre or head inwards / outwards. None of these had a marked effect on sibilance and midrange richness. I experimented with tilting the music centre or head away from / towards the listening axis and was quite surprised by what I found. Received wisdom would seem to suggest that tilting the tweeter away from the ears leads to less treble energy. In this case, maybe the coaxial driver is different in that tilting towards the ears increases midrange as well?

This has solved the problem of sibilance. There is also more midrange presence now. However, the sound is slightly congested and there is less air and separation among the instruments. The resulting sound is less 3D.

I like the current tone as it is but would like to get a more coherent sound overall with more focus and a larger degree of instrumental separation than I have now. If I tilt the head back away from my listening position, this won’t really help as I guess the sibilance will return.

Can you suggest how else I may adjust the speaker positioning? Do I do more or less toe in? Via the head or the rest of the speaker? Do I move the speaker further out from the wall behind it?

The one thing I haven't done is to adjust the height of the spikes - front relative to back - on the integral stand. I have found this to be tricky with other speakers in the past and would not know the effect or how to begin.

Thanks