Hi Ray,
Just about to crash here after a long day...
Unfortunately, you've purchased the wrong speakers. The right speakers for your DSP setup would be the Bavsound ones. They're specifically designed to make the 'best' of the oem DSP amplifier. They're the correct impedence and size to simply swap with the old drivers. They're priced at $397 USD currently which is around $239 cheaper than their usual price and that includes worldwide shipping.
This upgrade will make the current setup sound substantially better. If you adjust bass levels, you'll perhaps find a good setting which makes the best of the bavsound upgrade. The kit will replace the front tweeters and mid bass drivers, the midrange is left alone. There's another pair of mid bass drivers for the rear deck and a pair of tweeters to go in the rear doors (according to their website)
This will give you time to evaluate how you wish to progress for even better performance later (or sooner!) The reason is due to multiple routes forward. Some members will say to keep the oem head unit and amplifier and to upgrade the rear deck woofers to aftermarket ones. Other's will say to keep the oem DSP speakers you currently have and use the Dynavin N6 along with the GAS crossover to 'drive' the oem DSP speakers to a better level of efficiency, whilst others will suggest you remove the whole lot of oem modules and install a high quality head unit, amplifier and speakers for the potentially a much higher level of audio performance.
Each route has it's pro's and con's. I'd personally recommend the latter option of a complete new head unit, amplifiers and speakers. Other's will scorn at this due to not having 100% oem looks in the dash. Other's will compromise and go for the best of the cheap chinese head units which is the Dynavin if you wish to keep the oem DSP speakers, or the AVIN if you really want an Android experience for your head unit.
I'll explain each one so that it'll give you a better idea for each route.
1. Keeping OEM head unit, amplifier and speakers - Pro's = 100% oem looks in the dash and 100% OBC functionality. Con's = Expensive to get 'add on' products to enhance functionality, expensive to maintain the various modules as each has multiple points of failure and each one is 'relatively' expensive to fix/change/repair. To increase sound quality, all the oem modules need to be retained except the speakers. Equipment like a Sound Processor, amplifiers and speakers then need to be purchased and installed. If say the oem amplifier becomes faulty, then you must spend the money fixing/repairing it to continue using the setup. If the TFT screen in the monitor goes kaput, then it's more spend there again and so forth. If you wish to 'upgrade' the oem modules, there's some clever guys doing various things to the oem modules,like adding more powerful IC's, adding more modern Bluetooth, adding an Aux in etc etc, The prices for these additions soon adds up! - However, perhaps 'most' E39 M5 owners are the 'must be oem' type, so they don't mind the big costs that are/will be associated keeping everything working.
2. Aftermarket Chinese head unit - Pro's = oem'ish appearance and modern functionality all built into a single chassis unit to go into your dash. Cons = cheaply built and low end grade/quality internals and electronics. Reliability, performance and useability issues are very common with these units. Next to none or zero help/support from the sellers/manufacturers of the units. OBC is not retained. The 'best' choice for a chinese unit is the Dynavin N6 and/or the Avin Avant 2. The reason is that they're actually well supported by Jeff at J&T distributing ( I think the AVIN is supported by an enthusiast called Tommy) also, the N6 has a higher quality Digital to Analogue Converter (DAC) compared to all other cheap(er) chinese head units. It also has the benefit that it has some support for the display of some OBC data and, if you wish to retain the oem DSP speakers, then by also retaining the oem DSP amp, it will work via them. No other chinese unit offers these aspects. The AVIN I believe doesn't have the higher quality DAC nor the limited support of some OBC data nor the capability to retain the DSP speakers directly like the N6 does. However, it's driven by Android which offers the chance of more customisation etc. These are the two chinese unit's that I'd say are worth considering due to that excellent support. All the other's you'll see awash on ebay won't have the support and it's basically a gamble if you'll get a 'good' unit or not (most likely not !)
3. Aftermarket Premium brands. Pro's = high quality solutions, reputable and very well known brands, excellent build quality and the very latest technologies. Superior audio performance and also reliability, the best value for money by a significant margin (given all the criteria above), fully supported by proper after sales care and support if needed by thousands of independent car audio dealers all over many many countries around the world. Cons = not 100% oem looks and no OBC support.
Incidentally, for choice 3, if you do wish to retain the oem DSP speakers, then it's possible to do so by using the GAS E39 specific crossover. It allows you to fit the head unit of your choice and use an aftermarket 5 channel amplifier to then drive the oem DSP speakers with much better 'efficiency' resulting in a much better audio performance from them. You can also do this for the cheap chinese head units and the AVIN unit if you wish. The N6 is exempt as it can 'connect' to the oem DSP amp so no need for the GAS crossover and amplifier.
I hope the above makes it a bit clearer for you, I know you'll have questions still as there's still quite a bit within each of those for you to evaluate and consider. As mentioned, I personally prefer option 3 as I like my music to be reproduced fantastically well and I also like peace of mind and reliability knowing I have excellent quality products. I don't mind not having 100% oem looks in the dash, and I'm too busy enjoying driving to be worried about my Average speed or MPG figures!
If you have any questions or things you'd like to ask, post here and see what other members responses are and feel free to PM me. As this thread continues, I'll post up some pictures if you wish to help you understand more about the 3 main routes you'll need to consider
I have a brief rundown of my setup in my signature - the same 'design' could be done in your car too (minus the door builds and D pillar pods and door subs I have!)
Cheers, Dennis!