The original M 221 (1955) used a transformer designated as T 43, while the M 221 A (1956) used the T 44/1. The change from the latter to the A 925 appears to have occurred in about 1958; documentation in July of that year (M 221 F = version with Sogie output connector, made specifically for the French radio) shows "old" and "new" amplifier schematics (SB 92 and SB 93) with these two transformer types respectively.
After that, the A 925 is still shown in M 221 parts lists dated 1961, 1962, and even as late as September, 1971--and I don't have any Schoeps schematics or parts lists that refer to any "A700" transformer at all. That certainly doesn't mean that it never existed; there are significant gaps in Schoeps' own documentation from that period, let alone my subset of it. But I just don't see any reference to it.
--While interviewing people at Schoeps about the history of the company, I was told that Schoeps themselves had wound the transformers for the M 221 series, assigned individual serial numbers to them (!), and tested them individually to find the ones with the lowest distortion (said to be largely a function of how accurately the core laminations could be aligned). But I don't know whether this statement applied only to the A 925 (for example), or whether it applied to the other transformer types used in the M 221 series.
--best regards