I've heard this 80 percent figure before in reguards to how close the upgrade will bring the 5A to the performance level of the 7s. I have a couple problems with this.
1. As I recall even the upgrade is over $20,000 and involves sending the speakers back to California. For that expense and trouble I'd want to be a lot closer than 80 percent there.
2. This has to be an inaccurate estimate. I would think the 5A in it's native form would be closer to 90 percent as good as the 7s given how much we normally pay for audio upgrades for ever shrinking reurns.
It will be interesting to hear comparisons of the upgrade versus the 7s versus the 5A but it will be some time before that's even possible. For most of us, sticking with the 5A will likely make the most sense. Here's hoping I'm among the sensible ones, though I'm sure I will be tempted.