Mark Levinson pre-amplifiers compared

On advice from Audiogon discussants...and I thank them....I purchased a ML 523 and have
posted my ML 326-s for sale.

A review of the four ML pre-amplifiers I have owned may interest some.

1. ML 10 pre-amplifier....purchased around 1983 (and returned two weeks later) following a dealer's assertion that it incorporated the characteristics of that brand's more expensive pre-amplifiers, at a much lower price.
False !  It was dull and flat.
2. ML-7, purchased around 1983.  Narrowly chosen over the Spectral DMC-10 (I believe the alpha version).
The Spectral had the ethereal high end which the ML-7 entirely lacked, but at the sonic cost of a 'thin and
watery' mid-range and base.  The ML-7 within its frequency confines was magnificent.
I attempted 12 or so years ago to improve on it, borrowing the top-of-the line CJ solid state
pre-amp for comparison.  The ML-7 easily won.
3. ML 326-s, purchased two years ago.  Finally a conclusive improvement over the ML-7.
The high frequencies were extended and euphonic, the sound more detailed throughout the
sonic range, the tonal balance as accurate as my 'live' music listening experience allowed me to judge.
This is a wonderful pre-amplifier, its tonal neutrality, sweet high frequencies and sonic detail such that if I had not committed to the ML 523 I could forever be happy with it.
4. ML 523.    The sound is immediately distinguishable from that of the 326s.  The 523 offers an 'air transparency' and 'articulate transients' (to quote the Stereophile reviewer) that the 326s cannot match.  This was, to date, most obvious when listening to a choir performance, on vinyl.  The complex tonal characteristics of the different choir sections required no effort of imagination to differentiate, the spatial positioning was equally bold and 'observable', the 'air' around the voices and their high frequency transients a sonic treat.  ML 523 brought something new and irrepressibly enticing to my living room.
I must at the same time comment on the overall tonal balance of the ML 523 which in one sense...and perhaps I am wrong about this.. hewed closer to that of the ML-7 than to that of the ML 326s.   While the ML-7 more or less lacked a top 'top end', it has been described (accurately, I believe) as having 'slam and midrange punch'. The 523 has an overall fuller sound than that of the 326-s. and maintains what one might still call 'slam and punch' throughout the frequency spectrum.

Regarding loudspeakers, the ML 523 makes more evident the high frequency 'ring' and midrange 'bogginess' which render the B&W 802D2's less accurate than their 802D3 successors.  Those faults of the 802 D2's in particular respect of reproducing piano music
bring into perspective an aesthetic dilemma.  The D2's are gorgeous sculpted loudspeakers, D3's close to being eyesores.  Purchase of D2's 'upgraded' with the D3's high and mid-frequency sections, but retaining the woofer cabinetry of the D2, would for me be a no-brainer.  I said as much to B&W in an e-mail, but of course they did not reply.

Would replacing my 532h amplifier with a ML 534 make much difference ?

Thanks to all,
'seventies'