from Harbeth 30.1 to SHL5+, an upgrade or lateral move?

I had SHL5s some years ago and didn't really like them - I found them rather soft and woolly sounding, particularly in the bass. I sold them and moved on to something else for a few years.

More recently I came to hear the M30.1s and ended up buying a pair. I love them. They are far more neutral and natural sounding than the SHL5s in my 4 x 5m room. Bass is not all that deep, but it is tight and rhythmic. The M30.1s are also more extended and cleaner in the treble, and the midrange is more refined and more transparent.

So, personally, I would consider the SHL5 a downgrade from the M30.1s. But I wouldn't discourage you from hearing them - they may just be what you are looking for. But I agree with others that an amplifier or source upgrade may be a better option.

The M30.1s are truly amazing speakers and I would be interested to know why you are feeling the urge to upgrade them.

The SHL5 Plus does not sound soft and woolly as the SHL5. The bass of the SHL5+ is fuller, deeper, tighter and punchier than the M30.1. The largest difference or transformation between the SHL5 and SHL5+ is in the bass department apart from better integration between the drivers which in turn produces an overall smoother and more coherent presentation.

the shl5+ extends lower and have better bass overall. id say its a upgrade to go from 30.1 to shl5+.

I agree on many above and think that the shl5+ is like a 30.1 (wonderful midrange) but with deeper bass and more 3D feeling. I would want switch some day.