Halo A 51 Amplifier Listening Tests
Unbalanced Audition
I conducted my first audition session using the unbalanced inputs mainly because I did not have my XLR cables yet. All of my comparison comments are with respect to my reference amplifier, the Acurus A250. The A250 turned out to be a great reference amp because it is equally matched in power rating which made it similar enough for comparability.
Involvement
When doing so, I began my two channel audition with the 70s art rock band Yes's CD, "The Ladder," as these reference songs have the involvement and dynamics I seek when comparing product performance. With the Parasound amps driving my speakers, Jon Anderson's voice was forward as the keyboards carried the energy without any audio blemishes, reproducing the pace and rhythm perfectly. After listening to Yes I moved on to the "West" CD by Annie Lennox. I cranked the volume way up and found myself free of that inhibiting audio alarm in my head that nags at me to turn it back down. Using the Parasound amp allowed my speakers to portray every aspect that I had come to expect without adding any noticable sign of distortion or flaw. When implementing the unbalanced section it was challenging to identify these subtle differences found between the Parasound Halo amplifiers and the Acurus reference amplifier. But that most certainly proved to not be the case during our balanced audition as discussed later in this article.
Sound Stage & Imaging
Turning my attention to "Malcolm Makes Haaj" I was able to verify that the Parasound allowed my speakers to place the imaging exactly as anticipated though the sound stage perhaps seemed a tad bit lower than the Acurus. Moving on I recognized that the instruments sounded natural and real and in fact, the drum solo even had more punch and rigidity than the Acurus.
Transparency & Airiness
On Enya's "Marble Halls" the Halo amplifiers again did a stellar job of optimizing the performance of my speakers allowing them to accurately reproduce this incredible recording.
Her voice was clear and detailed with just the right amount of sibilance.
Detail & Dynamics
When auditioning the Flim & the BB's "Big Notes" CD, I didn't hear any merging of instruments nor was there any sign of compression going from soft to loud as the Parasound Halo amps powered my speakers with perfect clarity.
Tonal Balance
With the Parasound amplifiers firing away, I turned my audition to Patrick O'hearn's "Trust" CD. It was then that I noticed a significant improvement in driving my speakers to their maximum potential when in ways simply not found with other amplifiers in my system, including the Acurus reference amp. The bass extension was obviously more pronounced and powerful. I verified this with Steely Dan's "Two Against Nature" when I noticed that the bass guitar with the Parasound amplifier stood out with much more authority than the Acurus. The mid and high frequencies sounded a bit more uniform and balanced with all music sources.
Balanced Audition
After finally receiving my balanced XLR cables from AV Cables I was eager to implement them in my reference system to begin my investigative audition via balanced inputs. With little prior experience with XLR connections, I doubted that I would be able to hear significant change or improvement, but I quickly found that I was dead wrong. When implementing the XLR balanced connections, it was instantly recognized by me and others around me that the sound quality and dynamics improved as the soundstage and tonal signature became more refined. The presence of the music also became more detailed as the bass tightened with significant authority, and most importantly to me, the sound stage elevated. The subtle differences noticed during unbalanced play between the Acurus and Parasound amplifiers suddenly became much more pronounced. It is important to note that the Halo amps were being fed by the Integra Research RDC-7. With other processors or receivers capable of only doing a phase split to give their balanced output the results might not be as impressive. Based on my audition, it seemed obvious that the balanced inputs were definitely the preferred and optimum configuration for the Halo amplifiers.
To sum up my listening sessions the Parasound A 21 amp was very close in sound to the Acurus A250. The Parasound had tighter bass which is probably attributed to a better damping factor. The sound stage was a little lower than the Acurus which is a minor difference to many people. But wait, that is for the unbalanced listening. The balanced inputs added a whole new dimension of sound compared with the Acurus. The A 21 seems to be designed more for balanced inputs than unbalanced. Sure, it sounds good with unbalanced but it really bloomed with the balanced inputs.
