Twochannel Reference Build — Neutral Measured Separates

For a listener who wants the system to step aside and leave the recording, in a dedicated room where accuracy is the aim and separate boxes are welcome. The Revel's flat voicing sets the brief; the Parasound supplies the current the load demands, while the Lumin and the Krell are picked to stay out of the way.

Revel voices the Ultima Studio to a measured flat response rather than a house character, and a speaker built that way makes the electronics ahead of it audible: there is no deliberate warmth or forwardness to mask what the amplifier and source contribute. The Studio is a three-way carrying five drivers, an 87dB sensitivity, and a 6-ohm nominal impedance that falls to 3 ohms; its pair of 8-inch woofers cross to the midrange at 2200Hz and reach 31Hz in-room. That 3-ohm minimum is the figure that dictates the amplifier. Parasound's A21+ answers it with 300 watts into 8 ohms, 500 into 4, and stability all the way to 1.5 ohms, backed by a damping factor of 1100. That damping number — an output impedance of a few thousandths of an ohm — is what pins the Studio's woofers to the signal through the impedance dip, so the bottom two octaves stay defined instead of slurring. Its high-bias Class A/AB stage runs in Class A for the first several watts, which is where most domestic listening actually sits. Between them, the Krell KCT is a balanced line stage measuring 0.005 percent distortion, there to set level and switch inputs without laying tone over the signal. The Lumin T2 feeds it, converting through an ESS ES9038PRO and running at fixed output so the Krell owns the volume. Because the Revel imposes no signature of its own, what reaches the room is the sum of a clean converter, a neutral line stage, and an amplifier with the current to govern a hard load. Take away the A21+'s grip and the Studio's low end loses its outline first, before anything higher in the band gives way.

Neutrality is exposure, and this arrangement hides nothing: bright, sibilant, or compressed recordings arrive with their faults intact, so a library heavy in loud modern masters can turn hard through the Revel's flat top end. The A21+ runs warm and pulls real current at idle, wanting ventilation and a sturdy rack. The Krell KCT's CAST connection gives its best only into matching Krell amplifiers; run single-ended or balanced into the Parasound it works fully but leaves that feature dormant. And though the Studio reaches 31Hz, the lowest pedal of a pipe organ and the floor of electronic bass still call for a subwoofer, which then needs its crossover set carefully to preserve the neutral balance.

• 01

  Swap A21+ → AHB2 (−$1,501)

  Swapping the A21+ for the Benchmark AHB2 drops distortion and noise close to the measurement floor, but its 100 watts into 8 ohms give up the Parasound's headroom into the Studio's 3-ohm dip. Better suited to nearer-field or lower-SPL rooms, or run as a bridged pair to recover the current.

• 02

  Swap Ultima Studio → 802 D3 (+$4,000)

  For deeper bass and a diamond-dome top, the B&W 802 D3 raises the speaker spend well past the rest of the system, trading the Revel's studio-flat balance for B&W's slightly more lit presence region. The A21+'s current reserve drives its 3-ohm load without complaint.