I’m a Denon advocate, so my opinion is biased. They are a feature rich receiver and have been very reliable with few to zero bugs. I hate dealing with bugs and have found that Denon has fewer than other brands. Also, the Denon GUI on their mid to higher level receivers is excellent. So having said that, the 991 is quite a machine for the price. Unfortunately, it does not have pre-outs. You need to move up to the 3311 to get pre outs. If you want to stick with Denon, the 3311 is the one that I would buy, considering your price point. The 991 and 3311 are sister receivers with the 3311 adding some custom installer type functions. Be warned though, neither have independent sub calibration capabilities despite having two sub pre outs. They have a mirror operation. I am hopeful that Denon will add a receiver with all the features of the 3311 plus dual sub calibration capabilities and the ability to use both height and width speakers simultaneously. At least that’s why I have not moved from my 3808 yet.
You are SOL on finding a pre at your price point unless you are OK with buying used.
