My principle of playing milongas/valses is simple: always, always the most popular tunes only. Never experiment with milongas/valses. There are several reasons for it, the most obvious being that the number of milongas or valses tandas you can play throughout the night is very limited. It is almost once every hour, and DJs need to bear in mind that for people who like milongas/valses, they have to wait five tandas to have one. It will seriously upset them if they hear something unappealing after a long wait. The dancing mood will be adversely affected, and irreversibly so.
Another reason, which is more geographically specific, may be that Asians are generally less good in interpreting milonga and vals music. Milonga/vals music is faster, demands good sense of rhythm, and allows less room for pauses. These coincide with general weaknesses in Asian people’s dancing, so I tend to observe that milonga/vals is a more difficult genre of music for Asian dancers. It will ease the situation if the tunes played are familiar to the dancers’ ears; otherwise, the scene could be a bit disastrous to watch sometimes. Even for people who are fond of and good at milonga/vals music, most definitely prefer the classics than unknown stuffs. Not even one tanda a night, por favor.
If you have to introduce a very good but unheard / less heard milonga/vals, please make sure: (1) it has normal rhythm and basically predictable phrasing; (2) it comes as the second song of a tanda; and (3) it sits in harmony with other songs in the tanda and does not cut the energy or vary the flow.
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