marten design alto vs miles III Vs wilson sophia?

please help me , i have a choice to make between those speakers for a 600sp/ft room and for lowlevel listening sessions with plenty of grace and details..
I have not audition the Marten Alto. But I have no problem purchasing and living with the Avalon Indras, or Marten Miles III.

What are your Source (Digital/Analog), Pre and Power Amps (tube/SS)?

Avalon Indra (this should be on your list)
Miles III
Marten Alto
Wilson Sophia (not my cup of tea)
thanks, yes the avalon are on my list too , my source is digital and i will choose the amplifier after the speakers.. miles III are 91db , alto 87db not the same needs.:)
Tubes or SS for the amp?

Both Miles and Alto impedence are normally 4 ohms (and I'm sure you know this) but they drop to 3.9 to 3.8 so to get the max effort your amp should be matched correctly.

Alto for smaller rooms like my office would work great. If I move my system to spare room in my basement then I'm considering Indra and Miles III.
ceramic drivers sound more pleasant with tubes. i know one who uses antique sound lab asl hurricane monoblocks to drive the coltrane alto. 100 tube watts minimum. tubes are more live. for solid state i would recommend redwineaudio 70.2 / spectron musician monos or accuphase e-450 / gamut 150 / Pathos logos integrated. For digital Weiss DAC2 (=minerva but cheaper) or berkley alpha.

good luck
I own a pair of Marten Coltrane Altos, so I know from whence I speak. Firstly compared to the Miles 3, the Coltrane Altos are in another class. The Miles 3 is only the middle speaker in the Heritage line, whilst the Coltrane Alto was the entry level into the Coltrane line & featured the finest Accuton drivers, Jorma No1 internal wiring, ultra high grade crossover & a carbon/kevlar monocoque cabinet which 'disappears'.

The Avalon Indra is a $20k speaker & is very good, but lacks bi-wire connections. The Coltrane Alto listed for $24k 6 years ago. The Altos are more extended in the top end than the Indras, and because of the extreme quality of its components and design, I would expect the Altos to be a more refined and accurate speaker overall, and for me, ultimately a more satisfying speaker. In the end however, it comes down to personal preferences and taste. The Indras would be best suited to a medium size listening room.

If you're going to be doing mostly low level listening, I would have an audition of the Wilsons, and the Altos (if you can manage to locate a pair (virtually unobtanium!))