Sony STR-AZ7000ES Power Transformer vs Onkyo RZ70

When it comes to premium AV receivers, two names dominate the conversation: Sony STR-AZ7000ES and Onkyo RZ70. Both are flagship models from their respective brands, promising top-tier performance for home theater enthusiasts. However, one of the most critical components that often goes unnoticed is the power transformer—the heart of any AV receiver. In this detailed comparison, we’ll dive deep into how the Sony STR-AZ7000ES power transformer stacks up against the one inside the Onkyo RZ70.

Understanding Power Transformers in AV Receivers

Before comparing these two titans, it’s essential to understand the role of a power transformer. This component converts the incoming AC power into clean, stable current that feeds every part of the receiver—from audio amplification to digital signal processing. A high-quality transformer ensures:

• Consistent power delivery
• Low distortion
• Better heat management
• Stable performance at high volumes

Now, let’s break down both AV receivers and focus on their power delivery systems.

Sony STR-AZ7000ES Overview

Sony’s STR-AZ7000ES is the flagship model of its ES (Elevated Standard) lineup. It offers:

• 13.2 channels
• 150W per channel (8 ohms, 2ch driven)
• Custom 32-bit DACs
• High-current amplifier design
• Powerful toroidal transformer

Power Transformer Details

The Sony STR-AZ7000ES uses a custom-built, high-capacity toroidal power transformer. Unlike standard E-I core transformers, toroidal transformers offer:

• Lower magnetic leakage: Prevents interference with other internal circuits
• More efficient power transfer
• Compact but powerful design
• Quiet operation with less mechanical hum

Sony has paid close attention to the internal isolation of the transformer, which helps reduce vibration and electromagnetic noise—critical for audio fidelity in high-end receivers.

Onkyo RZ70 Overview

The Onkyo RZ70 is another heavyweight in the AV world. Part of Onkyo’s Reference Series, it features:

• 11.2 channels (expandable to 13.2 via pre-outs)
• 140W per channel (8 ohms, 2ch driven)
• THX Certified Select
• ESS Sabre DACs
• Ultra-high current amplification

Power Transformer Details

The Onkyo RZ70 uses a custom high-current, EI-core power transformer designed specifically for the RZ series. Key features include:

• Heavy-duty laminated EI core
• Thick winding for high current
• Isolated power supplies for digital and analog stages
• Thermal shielding for long life

While not toroidal, the EI-core design used by Onkyo is oversized and optimized for linear current delivery, making it ideal for dynamic audio scenes and surround sound effects.

Sony STR-AZ7000ES Power Transformer vs Onkyo RZ70: Head-to-Head

Let’s now directly compare the power transformer and related performance aspects of both receivers.

Audio Performance Comparison

Sony STR-AZ7000ES Sound Signature

Thanks to its toroidal transformer and ES audio engineering, the AZ7000ES delivers:

• Clean midrange
• Tight bass with high transient accuracy
• Wide dynamic range
• Very low noise floor, even at high volumes

It also benefits from Sony’s advanced Digital Cinema Auto Calibration IX (D.C.A.C. IX), allowing for room optimization with pinpoint accuracy.

Onkyo RZ70 Sound Signature

The RZ70 is no slouch either. It features:

• Lush, immersive surround effects
• High headroom for demanding audio scenes
• Warm mid-tones and rich bass
• Enhanced dialogue clarity, thanks to THX processing

Despite the EI-core transformer, Onkyo’s engineering ensures high current delivery, suitable for large home theaters.

Build Quality and Thermal Management

Sony STR-AZ7000ES

Sony isolates the transformer in a shielded compartment to prevent interference. Combined with a rigid chassis and independent heatsinks, it ensures long-term reliability.

Onkyo RZ70

The RZ70 uses a large cooling system with multiple heat sensors. Although the transformer can run hotter, its cooling mechanism compensates well during extended use.

Gaming and 8K Support

Both receivers come with HDMI 2.1 support, including:

• 8K/60Hz and 4K/120Hz passthrough
• VRR (Variable Refresh Rate)
• ALLM (Auto Low Latency Mode)
• HDR10, Dolby Vision, and HLG support

Power-wise, both can handle the demands of 8K content, but Sony’s transformer ensures quieter operation during gaming sessions.

Which Power Transformer Is Better?

Sony STR-AZ7000ES gets the edge here due to:

• Quieter, more efficient toroidal transformer
• Better isolation from electrical noise
• Compact design with robust output

Onkyo RZ70, on the other hand, offers:

• Strong linear current delivery
• Great performance for THX and DTS:X soundtracks
• Slightly more rugged build for analog purists

If silent operation, audiophile clarity, and compact yet powerful design matter most, Sony’s toroidal transformer wins. If raw analog power and slightly more aggressive dynamics appeal to you, Onkyo still holds its ground.

Price-to-Performance Ratio

While both are priced in the premium segment, Sony STR-AZ7000ES tends to be slightly more expensive due to its advanced transformer and ES series build quality. Onkyo RZ70 may offer better value if your system already includes external amplification.

Conclusion

In the battle of Sony STR-AZ7000ES power transformer vs Onkyo RZ70, the winner depends on your priorities:

• For audiophile precision, cleaner power, and quieter operation, go with the Sony STR-AZ7000ES.
• For dynamic output, THX-grade performance, and budget-friendliness, the Onkyo RZ70 is a fantastic alternative.

Both AV receivers offer excellent sound performance, future-proof HDMI features, and solid build quality. But when it comes to power transformer design, Sony’s toroidal engineering gives it a notable edge.

FAQs

Q1: Is a toroidal transformer better than EI-core in AV receivers?
Yes, toroidal transformers generally offer lower magnetic leakage, quieter operation, and better power efficiency.

Q2: Does transformer type affect audio quality?
Absolutely. The type, size, and design of the transformer directly impact noise levels, power stability, and overall sonic clarity.

Q3: Which is more future-proof—Sony STR-AZ7000ES or Onkyo RZ70?
Both are future-proof in terms of HDMI 2.1, 8K, and immersive audio formats, but Sony has a slight edge with 13.2 native channels.

Q4: Are these receivers suitable for large home theaters?
Yes, both models are designed for large rooms with demanding speaker setups, especially when paired with external amplifiers.