Simple answer is: If other Ads are non-contextual and do not look like AdSense units, then you can use with Adsense.
You can use other ad networks with Adsense as long as they do not violate Adsense TOS. For maximum revenue I would advice you to try rotating the ads and over a period of time check how ads fair and compare with country specific users.. I use Google admanager on my site and for USA visitors I normally avoid showing Adsense as other ad networks generate more revenue than Adsense. Well every site is different and so are the visitors you need to find out what works on your site and what does not. Keep tweaking and experimenting.