I had the very latest version before getting my Hovland HP-100 preamp. The P-5 plumbed deep in the bass and had a very clean but very slightly dark sound. The top to bottom continuousness was not in the same league as the HP-100 but you would not be disappointed till the HP-100 is inserted in the system and your tastes in music flushes this issue out. The P-5 worked well with a variety of amps I have around my house in various systems. The HP-100's highs seem to go out of sight into the cosmos yet are silky smooth. Some of the differences are obvious between the two preamps and some take longer listening sessions. Given the very low cost of widely available 3 tubes the Hovland uses and the fact there are only 3, this is hardly a hassle every few years. If it is a hassle our obesity problem is about to explode.
On looks the Hovland is stunning and always gets jaw drops from those that have never seen one whereas the P-5, while excellent fit and finish and a statement piece in its own right, did not conjure up that Rowlandish feeling of absolute top of the heap. As vain as this sounds I suspect Hovland owners will say this ads to pride of ownership.
In summary, I would say that the P-5 has deeper, more powerful bass like my former Sonic Frontiers SFL2, a very clean and delightful presentation, exceptional looks and an incredible value on the used market and will mate very well with a broader range of amps, than say, the Hovland HP-100.