I have extensive experience with the Yamaha A-S1100 and own the Parasound Halo integrated. Both amps were extensively compared in my system with the same components and recordings.
My conclusion was that both are very good. The Yamaha is slightly more natural sounding with strings and piano. It also has a leaner tonal balance. The Halo gives more "body" and heft to the music, but is very neutral. They are equal in detail retrieval and soundstage, but the Halo doesn't make an exhibition of its detail capability, its "sneaky." The Yamaha has a lower noise floor but it also strains more easily, and in some recordings, the Yamaha's treble can be slightly grainy. This is also the case with the much cheaper A-S500.
It takes a lot to strain the Halo and it's very clean under demanding loads. I must admit the Halo DAC and phono stage are overrated. Both are competent but nothing to write home about. For me, the Halo was the better all around amp, especially when factoring in the ~$2100 street price.
My conclusion was that both are very good. The Yamaha is slightly more natural sounding with strings and piano. It also has a leaner tonal balance. The Halo gives more "body" and heft to the music, but is very neutral. They are equal in detail retrieval and soundstage, but the Halo doesn't make an exhibition of its detail capability, its "sneaky." The Yamaha has a lower noise floor but it also strains more easily, and in some recordings, the Yamaha's treble can be slightly grainy. This is also the case with the much cheaper A-S500.
It takes a lot to strain the Halo and it's very clean under demanding loads. I must admit the Halo DAC and phono stage are overrated. Both are competent but nothing to write home about. For me, the Halo was the better all around amp, especially when factoring in the ~$2100 street price.