Box Dye + Your own developer?

[BombDiggity]

So lately I've been using L'Oreal Professional dyes to color my hair. I buy them at a local Beauty Supply Outlet here (The BSO to be specific) and I'm really happy with it but they don't have a wide range of reds and purples.. In the fall I want to go more of a darker purplish/brownish/blackish color. I've tried Sally's but they don't have this particular color either.

While browsing Shoppers Drugmart I took a stroll down the hair color isle and I found a couple fantastic colors that I love. The only thing that's off putting to me is that I hear the developers in box dyes are (mostly) extreme over kill. So do you think I could substitute one developer i.e. the one in the box for say a 20 volume developer I bought from a beauty supply store? Or do you think they wouldn't mix well?

If it matters these are the three shades I'm interested in:

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[Dragonfly]

My guess would be to mix a tiny amount of the two, and apply to some hairs underneath.

This way, if it doesn't work than not too much damage would occure or be noticed.

If it does look good, then do the rest.

You couldn't try mixing a L'oreal Professional red/purple and a dark brown to see if you can get a shade you like?

I have a feeling if you call L'Oreal, they wouldn't be very helpful to you.

Let us know what you decide to do - I might be tempted to try the same thing.